Refreshed patches based on:
https://sources.debian.org/patches/mupdf/1.17.0+ds1-1/0004-MuPDF-crossbuild-use-target-arch-pkg-config.patch/
https://sources.debian.org/patches/mupdf/1.17.0+ds1-1/0005-MuPDF-crossbuild-use-host-cc-for-utils.patch/
--- a/Makefile
+++ b/Makefile
@@ -134,6 +134,9 @@ PKCS7_OBJ := $(PKCS7_SRC:%.c=$(OUT)/%.o)
 
 HEXDUMP_EXE := $(OUT)/scripts/hexdump.exe
 
+$(HEXDUMP_EXE): scripts/hexdump.c
+	$(QUIET_CC) $(MKTGTDIR) ; $(CC_FOR_BUILD) $(CFLAGS) -o $@ $<
+
 FONT_BIN := $(sort $(wildcard resources/fonts/urw/*.cff))
 FONT_BIN += $(sort $(wildcard resources/fonts/han/*.ttc))
 FONT_BIN += $(sort $(wildcard resources/fonts/droid/*.ttf))
--- a/Makerules
+++ b/Makerules
@@ -15,6 +15,9 @@ OS := $(OS:MSYS%=MINGW)
 OS := $(OS:Windows_NT=MINGW)
 OS := $(OS:Darwin=MACOS)
 
+PKG_CONFIG ?= pkg-config
+CC_FOR_BUILD ?= $(CC)
+
 ifeq ($(findstring -fembed-bitcode,$(XCFLAGS)),)
   # clang does not support these in combination with -fembed-bitcode
   CFLAGS += -ffunction-sections -fdata-sections
@@ -101,35 +104,35 @@ else ifeq ($(OS),MACOS)
 else ifeq ($(OS),Linux)
   HAVE_OBJCOPY := yes
 
-  ifeq ($(shell pkg-config --exists freetype2 && echo yes),yes)
-	SYS_FREETYPE_CFLAGS := $(shell pkg-config --cflags freetype2)
-	SYS_FREETYPE_LIBS := $(shell pkg-config --libs freetype2)
+  ifeq ($(shell $(PKG_CONFIG) --exists freetype2 && echo yes),yes)
+	SYS_FREETYPE_CFLAGS := $(shell $(PKG_CONFIG) --cflags freetype2)
+	SYS_FREETYPE_LIBS := $(shell $(PKG_CONFIG) --libs freetype2)
   endif
-  ifeq ($(shell pkg-config --exists harfbuzz && echo yes),yes)
-	SYS_HARFBUZZ_CFLAGS := $(shell pkg-config --cflags harfbuzz)
-	SYS_HARFBUZZ_LIBS := $(shell pkg-config --libs harfbuzz)
+  ifeq ($(shell $(PKG_CONFIG) --exists harfbuzz && echo yes),yes)
+	SYS_HARFBUZZ_CFLAGS := $(shell $(PKG_CONFIG) --cflags harfbuzz)
+	SYS_HARFBUZZ_LIBS := $(shell $(PKG_CONFIG) --libs harfbuzz)
   endif
-  ifeq ($(shell pkg-config --exists lcms2 && echo yes),yes)
-	SYS_LCMS2_CFLAGS := $(shell pkg-config --cflags lcms2)
-	SYS_LCMS2_LIBS := $(shell pkg-config --libs lcms2)
+  ifeq ($(shell $(PKG_CONFIG) --exists lcms2 && echo yes),yes)
+	SYS_LCMS2_CFLAGS := $(shell $(PKG_CONFIG) --cflags lcms2)
+	SYS_LCMS2_LIBS := $(shell $(PKG_CONFIG) --libs lcms2)
   endif
-  ifeq ($(shell pkg-config --exists libjpeg && echo yes),yes)
-	SYS_LIBJPEG_CFLAGS := $(shell pkg-config --cflags libjpeg)
-	SYS_LIBJPEG_LIBS := $(shell pkg-config --libs libjpeg)
+  ifeq ($(shell $(PKG_CONFIG) --exists libjpeg && echo yes),yes)
+	SYS_LIBJPEG_CFLAGS := $(shell $(PKG_CONFIG) --cflags libjpeg)
+	SYS_LIBJPEG_LIBS := $(shell $(PKG_CONFIG) --libs libjpeg)
   endif
-  ifeq ($(shell pkg-config --exists libopenjp2 && echo yes),yes)
-	SYS_OPENJPEG_CFLAGS := $(shell pkg-config --cflags libopenjp2)
-	SYS_OPENJPEG_LIBS := $(shell pkg-config --libs libopenjp2)
+  ifeq ($(shell $(PKG_CONFIG) --exists libopenjp2 && echo yes),yes)
+	SYS_OPENJPEG_CFLAGS := $(shell $(PKG_CONFIG) --cflags libopenjp2)
+	SYS_OPENJPEG_LIBS := $(shell $(PKG_CONFIG) --libs libopenjp2)
   endif
-  ifeq ($(shell pkg-config --exists zlib && echo yes),yes)
-	SYS_ZLIB_CFLAGS := $(shell pkg-config --cflags zlib)
-	SYS_ZLIB_LIBS := $(shell pkg-config --libs zlib)
+  ifeq ($(shell $(PKG_CONFIG) --exists zlib && echo yes),yes)
+	SYS_ZLIB_CFLAGS := $(shell $(PKG_CONFIG) --cflags zlib)
+	SYS_ZLIB_LIBS := $(shell $(PKG_CONFIG) --libs zlib)
   endif
 
-  HAVE_SYS_CURL := $(shell pkg-config --exists libcurl && echo yes)
+  HAVE_SYS_CURL := $(shell $(PKG_CONFIG) --exists libcurl && echo yes)
   ifeq ($(HAVE_SYS_CURL),yes)
-	SYS_CURL_CFLAGS := $(shell pkg-config --cflags libcurl)
-	SYS_CURL_LIBS := $(shell pkg-config --libs libcurl)
+	SYS_CURL_CFLAGS := $(shell $(PKG_CONFIG) --cflags libcurl)
+	SYS_CURL_LIBS := $(shell $(PKG_CONFIG) --libs libcurl)
   endif
 
   HAVE_GLUT := yes
@@ -140,14 +143,14 @@ else ifeq ($(OS),Linux)
 
   HAVE_X11 := not-unless-portage-tells-me
   ifeq ($(HAVE_X11),yes)
-	X11_CFLAGS := $(shell pkg-config --cflags x11 xext)
-	X11_LIBS := $(shell pkg-config --libs x11 xext)
+	X11_CFLAGS := $(shell $(PKG_CONFIG) --cflags x11 xext)
+	X11_LIBS := $(shell $(PKG_CONFIG) --libs x11 xext)
   endif
 
   HAVE_LIBCRYPTO := not-unless-portage-tells-me
   ifeq ($(HAVE_LIBCRYPTO),yes)
-	LIBCRYPTO_CFLAGS := $(shell pkg-config --cflags libcrypto) -DHAVE_LIBCRYPTO
-	LIBCRYPTO_LIBS := $(shell pkg-config --libs libcrypto)
+	LIBCRYPTO_CFLAGS := $(shell $(PKG_CONFIG) --cflags libcrypto) -DHAVE_LIBCRYPTO
+	LIBCRYPTO_LIBS := $(shell $(PKG_CONFIG) --libs libcrypto)
   endif
 
   HAVE_PTHREAD := yes