libgo: remove -fplan9-extensions from CFLAGS

    
    Remove -fplan9-extensions from the CFLAGS used for libgo (no
    longer needed since the runtime was converted from C to Go).
    
    Reviewed-on: https://go-review.googlesource.com/82177

From-SVN: r255445

gcc/go/gofrontend/MERGE

-d16e370c93e2866a961847a15f5001413e66d179
+c02de8ca63f52a2475ce8645edee3203a3c908ac
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.

libgo/Makefile.am

@@ -40,7 +40,7 @@ AM_CPPFLAGS = -I $(srcdir)/runtime $(LIBFFIINCS) $(PTHREAD_CFLAGS)
 
 ACLOCAL_AMFLAGS = -I ./config -I ../config
 
-AM_CFLAGS = -fexceptions -fnon-call-exceptions -fplan9-extensions \
+AM_CFLAGS = -fexceptions -fnon-call-exceptions \
 	$(SPLIT_STACK) $(WARN_CFLAGS) \
 	$(STRINGOPS_FLAG) $(HWCAP_CFLAGS) $(OSCFLAGS) \
 	-I $(srcdir)/../libgcc -I $(srcdir)/../libbacktrace \

libgo/Makefile.in

@@ -458,7 +458,7 @@ WARN_CFLAGS = $(WARN_FLAGS) $(WERROR)
 # -I/-D flags to pass when compiling.
 AM_CPPFLAGS = -I $(srcdir)/runtime $(LIBFFIINCS) $(PTHREAD_CFLAGS)
 ACLOCAL_AMFLAGS = -I ./config -I ../config
-AM_CFLAGS = -fexceptions -fnon-call-exceptions -fplan9-extensions \
+AM_CFLAGS = -fexceptions -fnon-call-exceptions \
 	$(SPLIT_STACK) $(WARN_CFLAGS) \
 	$(STRINGOPS_FLAG) $(HWCAP_CFLAGS) $(OSCFLAGS) \
 	-I $(srcdir)/../libgcc -I $(srcdir)/../libbacktrace \