Build of GCC fails when . is in PATH

[caltry]

When cross compiling GCC while the current directory is in the PATH variable, compilation fails with the error message:

checking for i686-pc-linux-gnu-gcc... (cached) gcc
checking for C compiler default output file name... 
configure: error: in `/tmp/dcl9934/cross-tools/build-gcc/gcc':
configure: error: C compiler cannot create executables
See `config.log' for more details.

If you go to compile gcc manually, you'll see a more useful message:

$ rm -rf build-gcc && mkdir build-gcc
$ cd build-gcc
$ ../gcc-4.7.2/configure --target=arm-none-eabi --prefix=/tmp/dcl9934/cross-tools/local-prefix --enable-languages=c --without-headers
$ make
gcc -c   -g -O2 -DIN_GCC -DCROSS_DIRECTORY_STRUCTURE  -W -Wall -Wwrite-strings -Wcast-qual -Wstrict-prototypes -Wmissing-prototypes -Wmissing-format-attribute -pedantic -Wno-long-long -Wno-variadic-macros -Wno-overlength-strings -Wold-style-definition -Wc++-compat   -DHAVE_CONFIG_H -DGENERATOR_FILE -I. -Ibuild -I../../gcc-4.7.2/gcc -I../../gcc-4.7.2/gcc/build -I../../gcc-4.7.2/gcc/../include -I../../gcc-4.7.2/gcc/../libcpp/include  -I../../gcc-4.7.2/gcc/../libdecnumber -I../../gcc-4.7.2/gcc/../libdecnumber/dpd -I../libdecnumber    \
            -o build/genconstants.o ../../gcc-4.7.2/gcc/genconstants.c
/tmp/dcl9934/cross-tools/local-prefix/arm-none-eabi/bin/as: unrecognized option '--32'

This problem here is that GCC creates a symlink to the 'as' for the target platform, and puts it in the build-gcc/gcc directory. So, when we try to compile something for the host, we end up using the target's 'as' instead!

gcc$ which as
./as
gcc$ as --verbose
GNU assembler version 2.23.1 (arm-none-eabi) using BFD version (GNU Binutils) 2.23.1

Either the user need to remove '.' from their path, or we should remove it from the environment when we build GCC by submake.