gcc: fix parallel building (fixes #9212)

Tested building 5-times on an idle 8-core.

pkgs/development/compilers/gcc/4.9/default.nix

@@ -67,7 +67,7 @@ let version = "4.9.3";
     enableParallelBuilding = !langFortran;
 
     patches = [ ]
-      ++ optional enableParallelBuilding ../parallel-bconfig.patch
+      ++ optionals enableParallelBuilding [ ../parallel-bconfig.patch ./parallel-strsignal.patch ]
       ++ optional (cross != null) ../libstdc++-target.patch
       ++ optional noSysDirs ../no-sys-dirs.patch
       # The GNAT Makefiles did not pay attention to CFLAGS_FOR_TARGET for its

pkgs/development/compilers/gcc/4.9/parallel-strsignal.patch

@@ -0,0 +1,61 @@
+gcc/Makefile.in: fix parallel building failure
+
+The gcc-ar.o, gcc-nm.o, gcc-ranlib.o and errors.o included
+config.h which was a generated file. But no explicity rule
+to clarify the dependency. There was potential building
+failure while parallel make.
+
+For gcc-ar.o, gcc-nm.o and gcc-ranlib.o, they were compiled from one C
+source file gcc-ar.c, we add them to ALL_HOST_BACKEND_OBJS, so the
+'$(ALL_HOST_OBJS) : | $(generated_files)' rule could work for these
+objects.
+
+For errors.o, it is part of gengtype, and the gengtype generator program
+is special: Two versions are built. One is for the build machine, and one
+is for the host. We refered what gengtype-parse.o did (which also is part
+of gengtype).
+
+[GCC #61899]
+https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61899
+
+Upstream-Status: Send to gcc-patches@gcc.gnu.org mailing list
+
+Signed-off-by: Hongxu Jia <hongxu.jia@windriver.com>
+---
+ gcc/Makefile.in | 7 ++++++-
+ 1 file changed, 6 insertions(+), 1 deletion(-)
+
+diff --git a/gcc/Makefile.in b/gcc/Makefile.in
+index 6475cba..56e50bb 100644
+--- a/gcc/Makefile.in
++++ b/gcc/Makefile.in
+@@ -1481,13 +1481,16 @@ OBJS-libcommon-target = $(common_out_object_file) prefix.o params.o \
+ 	opts.o opts-common.o options.o vec.o hooks.o common/common-targhooks.o \
+ 	hash-table.o file-find.o
+ 
++# Objects compiled from one C source file gcc-ar.c
++OBJS-gcc-ar = gcc-ar.o gcc-nm.o gcc-ranlib.o
++
+ # This lists all host objects for the front ends.
+ ALL_HOST_FRONTEND_OBJS = $(foreach v,$(CONFIG_LANGUAGES),$($(v)_OBJS))
+ 
+ ALL_HOST_BACKEND_OBJS = $(GCC_OBJS) $(OBJS) $(OBJS-libcommon) \
+   $(OBJS-libcommon-target) @TREEBROWSER@ main.o c-family/cppspec.o \
+   $(COLLECT2_OBJS) $(EXTRA_GCC_OBJS) $(GCOV_OBJS) $(GCOV_DUMP_OBJS) \
+-  lto-wrapper.o
++  lto-wrapper.o $(OBJS-gcc-ar)
+ 
+ # This lists all host object files, whether they are included in this
+ # compilation or not.
+@@ -2437,6 +2440,8 @@ gengtype-parse.o: $(CONFIG_H)
+ CFLAGS-build/gengtype-parse.o += -DGENERATOR_FILE
+ build/gengtype-parse.o: $(BCONFIG_H)
+ 
++errors.o : $(CONFIG_H)
++
+ gengtype-state.o build/gengtype-state.o: gengtype-state.c $(SYSTEM_H) \
+   gengtype.h errors.h double-int.h version.h $(HASHTAB_H) $(OBSTACK_H) \
+   $(XREGEX_H)
+-- 
+1.8.1.2
+