test: fix spawn_stdout_and_stderr_to_file test on Android

S_IREAD and S_IWRITE are obsolete and not included in the Android
NDK's libc. More information:
http://www.gnu.org/savannah-checkouts/gnu/libc/manual/html_node/Permission-Bits.html
build: update android toolchain

gcc-4.7 has been removed in revision r9c. More info:
http://developer.android.com/tools/sdk/ndk/index.html#Revisions