Android ucontext_t handling refinement.
Android ucontext_t handling refinement.

This is a forward-compatible patch to prepare for future versions
of the Android C library headers that define ucontext_t.

When this patch is applied, Google Breakpad will build and work
properly against any version of the NDK or platform headers.

See http://code.google.com/p/android/issues/detail?id=34784 for
more context.
Review URL: https://breakpad.appspot.com/416002

git-svn-id: a14e546401035be51a469fbea25ecce70a1a22f2@1000 4c0a9323-5329-0410-9bdc-e9ce6186880e

tomgr/google-breakpad,tomgr/google-breakpad,tomgr/google-breakpad,tomgr/google-breakpad,tomgr/google-breakpad