regular expressions need to be reviewed

[killerbot]

I noticed that gcc 5.1 does not return 5.1 but 5 as result of gcc -dumpversion.

As such lots of options are suddenly not available anymore.

I myself will address already options_common_warnings.xml as a test case.

[Alpha]

I wonder how far back some of these version checks should be kept.  How likely is it that someone will have a new build of C::B, but be running gcc 4.6 (released 2011, last updated 2013)?

[oBFusCATed]

Centos 6 has gcc 4.4 as default compiler and many people use it a lot. Me included (I've migrated to clang though).
But there is a chance that I'll need to use gcc 4.4 sometime in the future.

Also it is not unheard of someone requiring the use of gcc 4.1 to make code compatible with Centos 5.
So we need to support them!

[Alpha]

Okay, makes sense.