This patches the compiler settings for chromium to remove
clang-specific settings, among other things.

Just do a `git apply --reject` to the unpacked chromium source when
it inevitably needs to be updated between versions.

--- a/build/config/compiler/BUILD.gn
+++ b/build/config/compiler/BUILD.gn
@@ -289,9 +289,7 @@ config("compiler") {
 
   configs += [
     # See the definitions below.
-    ":clang_revision",
     ":rustc_revision",
-    ":compiler_cpu_abi",
     ":compiler_codegen",
     ":compiler_deterministic",
   ]
@@ -732,7 +730,6 @@ config("compiler") {
         # toolchain has this flag.
         # We only use one version of LLVM within a build so there's no need to
         # upgrade debug info, which can be expensive since it runs the verifier.
-        ldflags += [ "-Wl,-mllvm,-disable-auto-upgrade-debug-info" ]
       }
     }
 
@@ -1406,27 +1403,6 @@ config("compiler_deterministic") {
   }
 }
 
-config("clang_revision") {
-  if (is_clang && clang_base_path == default_clang_base_path) {
-    update_args = [
-      "--print-revision",
-      "--verify-version=$clang_version",
-    ]
-    if (llvm_force_head_revision) {
-      update_args += [ "--llvm-force-head-revision" ]
-    }
-    clang_revision = exec_script("//tools/clang/scripts/update.py",
-                                 update_args,
-                                 "trim string")
-
-    # This is here so that all files get recompiled after a clang roll and
-    # when turning clang on or off. (defines are passed via the command line,
-    # and build system rebuild things when their commandline changes). Nothing
-    # should ever read this define.
-    defines = [ "CR_CLANG_REVISION=\"$clang_revision\"" ]
-  }
-}
-
 config("rustc_revision") {
   if (rustc_revision != "") {
     # Similar to the above config, this is here so that all files get recompiled
@@ -1716,7 +1692,7 @@ config("chromium_code") {
       defines = [ "_HAS_NODISCARD" ]
     }
   } else {
-    cflags = [ "-Wall" ]
+    cflags = []
     if (treat_warnings_as_errors) {
       cflags += [ "-Werror" ]
 
@@ -1725,10 +1701,6 @@ config("chromium_code") {
       # well.
       ldflags = [ "-Werror" ]
     }
-    if (is_clang) {
-      # Enable extra warnings for chromium_code when we control the compiler.
-      cflags += [ "-Wextra" ]
-    }
 
     if (treat_warnings_as_errors) {
       # Turn rustc warnings into the "deny" lint level, which produce compiler
@@ -1746,16 +1718,6 @@ config("chromium_code") {
       "__STDC_FORMAT_MACROS",
     ]
 
-    if (!is_debug && !using_sanitizer && current_cpu != "s390x" &&
-        current_cpu != "s390" && current_cpu != "ppc64" &&
-        current_cpu != "mips" && current_cpu != "mips64" &&
-        current_cpu != "riscv64" && current_cpu != "loong64") {
-      # Non-chromium code is not guaranteed to compile cleanly with
-      # _FORTIFY_SOURCE. Also, fortified build may fail when optimizations are
-      # disabled, so only do that for Release build.
-      defines += [ "_FORTIFY_SOURCE=2" ]
-    }
-
     if (is_apple) {
       cflags_objc = [ "-Wimplicit-retain-self" ]
       cflags_objcc = [ "-Wimplicit-retain-self" ]
@@ -2120,7 +2082,8 @@ config("default_stack_frames") {
 }
 
 # Default "optimization on" config.
-config("optimize") {
+config("optimize") { }
+config("xoptimize") {
   if (is_win) {
     if (chrome_pgo_phase != 2) {
       # Favor size over speed, /O1 must be before the common flags.
@@ -2179,7 +2142,8 @@ config("optimize") {
 }
 
 # Turn off optimizations.
-config("no_optimize") {
+config("no_optimize") { }
+config("xno_optimize") {
   if (is_win) {
     cflags = [
       "/Od",  # Disable optimization.
@@ -2219,7 +2183,8 @@ config("no_optimize") {
 # Turns up the optimization level. On Windows, this implies whole program
 # optimization and link-time code generation which is very expensive and should
 # be used sparingly.
-config("optimize_max") {
+config("optimize_max") { }
+config("xoptimize_max") {
   if (is_nacl && is_nacl_irt) {
     # The NaCl IRT is a special case and always wants its own config.
     # Various components do:
@@ -2252,7 +2217,8 @@ config("optimize_max") {
 #
 # TODO(crbug.com/621335) - rework how all of these configs are related
 # so that we don't need this disclaimer.
-config("optimize_speed") {
+config("optimize_speed") { }
+config("xoptimize_speed") {
   if (is_nacl && is_nacl_irt) {
     # The NaCl IRT is a special case and always wants its own config.
     # Various components do:
@@ -2278,7 +2244,8 @@ config("optimize_speed") {
   }
 }
 
-config("optimize_fuzzing") {
+config("optimize_fuzzing") { }
+config("xoptimize_fuzzing") {
   cflags = [ "-O1" ] + common_optimize_on_cflags
   rustflags = [ "-Copt-level=1" ]
   ldflags = common_optimize_on_ldflags
@@ -2403,7 +2370,8 @@ config("win_pdbaltpath") {
 }
 
 # Full symbols.
-config("symbols") {
+config("symbols") { }
+config("xsymbols") {
   rustflags = []
   if (is_win) {
     if (is_clang) {
@@ -2546,7 +2514,8 @@ config("symbols") {
 # Minimal symbols.
 # This config guarantees to hold symbol for stack trace which are shown to user
 # when crash happens in unittests running on buildbot.
-config("minimal_symbols") {
+config("minimal_symbols") { }
+config("xminimal_symbols") {
   if (is_win) {
     # Functions, files, and line tables only.
     cflags = []
@@ -2620,7 +2589,8 @@ config("minimal_symbols") {
 # This configuration contains function names only. That is, the compiler is
 # told to not generate debug information and the linker then just puts function
 # names in the final debug information.
-config("no_symbols") {
+config("no_symbols") { }
+config("xno_symbols") {
   if (is_win) {
     ldflags = [ "/DEBUG" ]