* The check for hybrids sometimes didn't work because the end of line
from the compiler output was stripped. Make sure there is always a
newline in the string so the regexp can match.
* The path prefix for SDL sub-libraries (image, ttf and mixer) are
wrong. Add the correct prefix, but leave the wrong ones for backward
compatibility.
Checking for the compiler version at packaging time doesn't work. So, do
it earlier and export a variable for it.
Also fix some variable names to make a check work and avoid cmake
failing in strange ways later on.
* common/ dir is no more.
* When using distcc, our logic to detect the secondary architecture
didn't work because cmake ran "distcc" instad of "distcc gcc-x86". Add
the missing part to the command-line invocation.
* If we don't do that, ninja will fail building WebKit because of a too
long command line
* CMake will use a "response file" to forward arguments when the
command line gets over the limit (with a safety margin)
