gcc8 patches

[Jason Bacon <outpaddling%yahoo.com@localhost>]

These are the patches needed to get gcc8 working on CentOS 7.

The c99 requirement is the same as for gcc7.

For gcc8, --with-system-zlib was set unconditionally, which caused the 
breakage for CentOS since it doesn't have zlib in base.  This probably 
affects other platforms as well, but I took the conservative approach 
and only fixed it for Linux.

Please respond if you have any concerns about these changes.

Thanks,

    JB

Index: Makefile
===================================================================
RCS file: /cvsroot/pkgsrc/lang/gcc8/Makefile,v
retrieving revision 1.13
diff -u -r1.13 Makefile
--- Makefile    12 Feb 2020 05:02:11 -0000    1.13
+++ Makefile    2 Mar 2020 19:49:44 -0000
@@ -23,7 +23,7 @@

 NOT_FOR_PLATFORM=    Interix-*-*

-USE_LANGUAGES=        c c++
+USE_LANGUAGES=        c99 c++
 USE_TOOLS+=        gmake makeinfo sed:run tar:build
 USE_TOOLS.NetBSD+=    gsed

@@ -38,7 +38,6 @@
 GNU_CONFIGURE_PREFIX=    ${GCC_PREFIX}
 INFO_FILES=        yes
 CONFIGURE_ARGS+=    --disable-libstdcxx-pch
-CONFIGURE_ARGS+=    --with-system-zlib

 UNLIMIT_RESOURCES+=    datasize
 UNLIMIT_RESOURCES+=    stacksize
@@ -101,6 +100,10 @@
 CONFIGURE_ARGS+=    --enable-libssp
 .endif

+.if empty(MACHINE_PLATFORM:MLinux-*-*)
+CONFIGURE_ARGS+=    --with-system-zlib
+.endif
+
 ## For target librarys and libjava programs.
 CONFIGURE_ENV+=        LDFLAGS_FOR_TARGET=${LDFLAGS_FOR_TARGET:Q}