[Pixman] Basic infrastructure for MIPS architecture and initial set of SRC routines.

[Nemanja Lukic]

Per previous code review:

Run time detection is still there (per Siarhei's comments), uses /proc/cpuinfo,
but now properly detects DSPr2 extensions and 32 byte cache line size (both are
true only for MIPS 74Kc cores).
  - Currently only 74Kc core is available that supports DSPr2.
  - In the future, when M14KE, 1074Kc cores (and others) become available we
    can add those also to the search string.
-mdspr2 compiler flag is automatically enabled for MIPS platforms. It can be
disabled at configure time for chips that doesn't support it.

Best Regards,
Nemanja Lukic