perf tools: Check if /dev/null can be used as the -o gcc argument

At least on Debian PARISC64, using:

acme@parisc:~/git/linux-2.6-tip$ gcc -v
Using built-in specs.
Target: hppa-linux-gnu
Configured with: ../src/configure -v --with-pkgversion='Debian
4.3.4-6' --with-bugurl=file:///usr/share/doc/gcc-4.3/README.Bugs


--enable-languages=c,c++,fortran,objc,obj-c++ --prefix=/usr
--enable-shared --enable-multiarch --enable-linker-build-id --with-system-zlib --libexecdir=/usr/lib --without-included-gettext --enable-threads=posix --enable-nls --with-gxx-include-dir=/usr/include/c++/4.3 --program-suffix=-4.3 --enable-clocale=gnu --enable-libstdcxx-debug --enable-objc-gc --enable-mpfr --disable-libssp --enable-checking=release --build=hppa-linux-gnu --host=hppa-linux-gnu --target=hppa-linux-gnu Thread model: posix gcc version 4.3.4 (Debian 4.3.4-6)

there are issues about using 'gcc -o /dev/null':

/usr/bin/ld: final link failed: File truncated
collect2: ld returned 1 exit status

So we test that and use /dev/null in environments where it
works, while using an .INTERMEDIATE file on those where it can't
be used, so that the .perf.dev.null file can be used instead and
then deleted when make exits.

Researched-with: Kyle McMartin <kyle@mcmartin.ca>
Researched-with: Mauro Carvalho Chehab <mchehab@redhat.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1263293910-8484-2-git-send-email-acme@infradead.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>