scripts/ver_linux use 'gcc -dumpversion'

These magic greps and hacks in ver_linux to get the gcc version always break after some gcc releases.

Since now gcc >4.3 allows compiling with '--with-pkgversion' ( which can be everything 'My Cool Gcc' or something )
ver_linux will report random junk for these.

Simply use 'gcc -dumpversion' to get the gcc version which should always work.

Signed-off-by: Gabriel C <nix.or.die@googlemail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>