Rename cpufeatures symbols to avoid colisions in static builds

This fixes potential duplicated symbols in static links
with other libraries including the cpufeatures.o object file
Remove trailing whitespace in the source files
Merge pull request #579 from ylatuya/cpufeatures

Rename cpufeatures symbols to avoid colisions in static builds
Merge pull request #650 from mstorsjo/remove-trailing-whitespace

Remove trailing whitespace in the source files