[libunwind] Remove __ANDROID_API__ < 18 workaround

https://github.com/android/ndk/wiki/Changelog-r24 shows that the NDK has
moved forward to at least a minimum target API of 19. Remove old workaround.

Reviewed By: #libunwind, danalbert

Differential Revision: https://reviews.llvm.org/D131792

NOKEYCHECK=True
GitOrigin-RevId: b559777c308dcdf40a5dc8dffd35867083a46c3c
1 file changed
tree: 39640a9d78a7a41b10861cfc5911b451ccf2e35e
  1. cmake/
  2. docs/
  3. include/
  4. src/
  5. test/
  6. .clang-format
  7. CMakeLists.txt
  8. LICENSE.TXT