-Wno-long-long causing stage2 build failure

[Laurent Guerby <guerby at acm dot org>]

It looks like configure correctly finds out that the GCC 2.8.1 I'm
using does not support -Wno-long-long, but when entering stage2 we're
still using the build compiler for compiling gengenrtl, and due to
some Makefile black magic we're incorrectly passing -Wno-long-long to
it, hence error.

I assume that the bootstrap process with the current CVS sources will
fail when not using a recent GCC as build compiler or not using GCC at
all.

Sorry if this is a duplicate, workaround is trivial: remove
-Wno-long-long.

-- 
Laurent Guerby <guerby@acm.org>

...
checking whether gcc accepts -Wno-long-long... no
...
make[2]: Leaving directory `/home/guerby/work/gcc/build/gcc'
echo timestamp > stage1_copy
echo stage2_build > stage_last
make CC="stage1/xgcc -Bstage1/ -B/home/guerby/work/gcc/install/i686-pc-linux-gnu/bin/" \
	 STAGE_PREFIX=stage1/ \
	 HOST_CC="gcc" CFLAGS="-g -O2" LDFLAGS="" WARN_CFLAGS="\$(GCC_WARN_CFLAGS)" STRICT_WARN="-Wtraditional -pedantic -Wno-long-long" libdir=/home/guerby/work/gcc/install/lib LANGUAGES="c gcov ada" MAKEOVERRIDES= OUTPUT_OPTION="-o \$@"
make[2]: Entering directory `/home/guerby/work/gcc/build/gcc'
gcc -c  -DIN_GCC    -g -O2 -W -Wall -Wwrite-strings -Wstrict-prototypes -Wmissing-prototypes -Wtraditional -pedantic -Wno-long-long  -DHAVE_CONFIG_H -DGENERATOR_FILE    -I. -I. -I../../gcc/gcc -I../../gcc/gcc/. -I../../gcc/gcc/config -I../../gcc/gcc/../include ../../gcc/gcc/gengenrtl.c
cc1: Invalid option `-Wno-long-long'