intrin: __rdtsc is not available on ARM

git-svn-id: https://svn.code.sf.net/p/mingw-w64/code@6629 4407c894-4637-0410-b4f5-ada5f102cad1
CRT_fp10: Add ARM implementation

git-svn-id: https://svn.code.sf.net/p/mingw-w64/code@6630 4407c894-4637-0410-b4f5-ada5f102cad1