Ensure _GNU_SOURCE is now longer defined on powerpc64 (which was a

regression from the GCC 8 series).

The technical background is that a consolidation in upstream GCC made
non-GNU platforms include gnu-user.h and then undefined some macros
in rs6000/freebsd.h, but missed doing the same in rs6000/freebsd64.h.

The has now been included upstream and the current snapshot that the
lang/gcc9-devel port tracks; carrying files/patch-powerpc64-no-_GNU_SOURCE
in this port should become obsolete with the GCC 9.2 release.

(As this should be a very short-lived measure, bump PORTREVISION only
for powerpc64 to avoid all other users having to rebuild, too.)

PR:		239648

lang/gcc9/Makefile

@@ -61,6 +61,7 @@ CONFIGURE_ARGS+=	--disable-multilib
 CONFIGURE_TARGET=	x86_64-portbld-${OPSYS:tl}${OSREL}
 
 .elif ${ARCH} == powerpc64
+PORTREVISION=	2
 CONFIGURE_ENV+=	UNAME_m="powerpc64"
 USE_GCC=	8
 .endif

lang/gcc9/files/patch-powerpc64-no-_GNU_SOURCE

@@ -0,0 +1,27 @@
+r274105 | amodra | 2019-08-05 01:52:33 +0000
+
+PR91349, powerpc64*-*-freebsd* defines _GNU_SOURCE
+
+rev 266496 (git ab6b1bb456) undefined some macros in rs6000/freebsd.h
+but missed doing the same in rs6000/freebsd64.h.
+
+        PR target/91349
+        * config/rs6000/freebsd64.h (CPLUSPLUS_CPP_SPEC),
+        (LINK_GCC_C_SEQUENCE_SPEC): Undef.
+
+--- UTC
+Index: gcc/config/rs6000/freebsd64.h
+===================================================================
+--- gcc/config/rs6000/freebsd64.h	(revision 274104)
++++ gcc/config/rs6000/freebsd64.h	(revision 274105)
+@@ -17,6 +17,10 @@
+    along with GCC; see the file COPYING3.  If not see
+    <http://www.gnu.org/licenses/>.  */
+ 
++/* Undef gnu-user.h macros we don't want.  */
++#undef CPLUSPLUS_CPP_SPEC
++#undef LINK_GCC_C_SEQUENCE_SPEC
++
+ /* Override the defaults, which exist to force the proper definition.  */
+ 
+ #ifdef IN_LIBGCC2