Work around a binutils bug on powerpc64 where the TOC would not be

properly reloaded when calling _fini() in large binaries with multiple
TOC sections (e.g. GCC), leading to a segmentation fault. Adding -mlongcall
to crt1 flags causes the compiler to emit explicit TOC load instructions
for all function calls, including _fini().

Reviewed by:	kib
Pointy hat to:	kib

lib/csu/powerpc64/Makefile

@@ -6,7 +6,8 @@ SRCS=		crt1.c crti.S crtn.S
 OBJS=		${SRCS:N*.h:R:S/$/.o/g}
 OBJS+=		Scrt1.o gcrt1.o
 CFLAGS+=	-I${.CURDIR}/../common \
-		-I${.CURDIR}/../../libc/include
+		-I${.CURDIR}/../../libc/include \
+		-mlongcall
 
 all: ${OBJS}