Update MinGW prebuilts from build 4991177

Bug: http://b/113171785
Bug: http://b/91353691

Key changes:
- Build winpthread and libgcc_s dlls with --dynamic-base, --nxcompat,
--high-entropy-va linker flags.
- Changes for libc++ for Windows
  - headers: Add casts in ua_wcs*chr in stralign.h
  - intrincs: check for __rdtsc

Test: Build AOSP, llvm-toolchain in addition to TH testing

Change-Id: If65dbc3e67a40d0c17c7ccb0425ee611694a67a9
1711 files changed