encoder: use more portable %PRIu64, define __STDC_FORMAT_MACROS

Older GCC versions and clang require __STDC_FORMAT_MACROS to be defined prior to
including stdint.h when compiling for C++, in order for PRIu64 and friends to be
defined

--HG--
branch : stable
aq: Bug Fixes in aq , ssim when ctu size is not set as 64.

1.Calculate qp offset for CU based maxCuSize set in FrameEncoder::calcQpForCu
2.Fix height for ssim computation based on maxCuHeight in FrameFilter::processRowPost

--HG--
branch : stable
Fix to eliminate unwanted application of weight in some (ref, enc) pairs

--HG--
branch : stable
encoder: change default frameNumThreads for 4-core HT CPUs to 3

--HG--
branch : stable
cmake: gcc flag introspection to fix Mac OS X 10.6 build

--HG--
branch : stable
RD merge: refine merge costs with estimated merge mode bits.
presets: modifications to smoothen the performance-efficiency plot.

--HG--
branch : stable
vec: tab to spaces

--HG--
branch : stable
Merge with stable
compress: disable EARLY_EXIT and TOP_SKIP (temporarily)
compress: save best bits, sad in xcomputeCostIntrainInter
compress: save distortion info in xComputeCostInter.
compress: cleanup
presets: correct bframes in "slow" to 4

--HG--
branch : stable
Merge from stable