ffbuild: Avoid using the --preprocessor argument to windres

Instead use --preprocessor-arg; in binutils 2.36, the --preprocessor
flag was changed so that it no longer accepts a string containing
multiple arguments, but the whole --preprocessor argument is
treated as the path to the preprocessor executable (where the path
can contain spaces).

It's currently unclear whether this behaviour will stay or if it
is going to be reverted in the future, see discussion at [1]. Just
to be safe, avoid using the --preprocessor argument. Don't redeclare
the full preprocessing command, but just add the $(CC_DEPFLAGS) options.

Based on a patch by Kyle Schwartz.

[1] https://sourceware.org/bugzilla/show_bug.cgi?id=27594

Signed-off-by: Martin Storsjö <martin@martin.st>

configure

@@ -6917,7 +6917,6 @@ LD_LIB=$LD_LIB
 LD_PATH=$LD_PATH
 DLLTOOL=$dlltool
 WINDRES=$windres
-DEPWINDRES=$dep_cc
 DOXYGEN=$doxygen
 LDFLAGS=$LDFLAGS
 LDEXEFLAGS=$LDEXEFLAGS

ffbuild/common.mak

@@ -83,7 +83,7 @@ COMPILE_NVCC = $(call COMPILE,NVCC)
 	-$(if $(ASMSTRIPFLAGS), $(STRIP) $(ASMSTRIPFLAGS) $@)
 
 %.o: %.rc
-	$(WINDRES) $(IFLAGS) --preprocessor "$(DEPWINDRES) -E -xc-header -DRC_INVOKED $(CC_DEPFLAGS)" -o $@ $<
+	$(WINDRES) $(IFLAGS) $(foreach ARG,$(CC_DEPFLAGS),--preprocessor-arg "$(ARG)") -o $@ $<
 
 %.i: %.c
 	$(CC) $(CCFLAGS) $(CC_E) $<