#2 Fix gcc version detection

[Ville Skyttä]

gcc version detection is broken on newer versions of
gcc, where --version returns a verbose value.
-dumpversion should work everywhere. Fix attached.

Here's an example of what my "gcc --version" and "gcc
-dumpversion" outputs on Fedora Core 2:

$ gcc --version
gcc (GCC) 3.3.3 20040412 (Red Hat Linux 3.3.3-7)
Copyright (C) 2003 Free Software Foundation, Inc.
This is free software; see the source for copying
conditions. There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A
PARTICULAR PURPOSE.

$ gcc -dumpversion
3.3.3

[Ville Skyttä]

Fix gcc version detection