the wart util is used at build time only, so use BUILD_* so we can cross-compile

--- a/makefile
+++ b/makefile
@@ -1406,12 +1406,17 @@
 
 ckctel.$(EXT): ckcsym.h ckcdeb.h ckcker.h ckcnet.h ckctel.h ckclib.h
 
+BUILD_CC ?= $(CC)
+BUILD_CFLAGS ?= $(CFLAGS)
+BUILD_CPPFLAGS ?= $(CPPFLAGS)
+BUILD_LDFLAGS ?= $(LDFLAGS)
 wart: ckwart.$(EXT)
-	$(CC) $(LNKFLAGS) -o wart ckwart.$(EXT) $(LIBS)
+	$(BUILD_CC) $(BUILD_CFLAGS) $(BUILD_CPPFLAGS) -o wart ckwart.$(EXT) $(BUILD_LDFLAGS)
 
 ckcmdb.$(EXT): ckcmdb.c ckcdeb.h ckcsym.h ckclib.h
 
 ckwart.$(EXT): ckwart.c
+	$(BUILD_CC) $(BUILD_CFLAGS) $(BUILD_CPPFLAGS) -o $@ -c $<
 
 ckudia.$(EXT): ckudia.c ckcker.h ckcdeb.h ckucmd.h ckcasc.h ckcsym.h ckcsig.h \
 		ckcnet.h ckctel.h ckclib.h