[PATCH android/bionic 0/3] Reduce code size of libc and libm by GCC visibility

The following set of Android bionic patches use GCC visibility pragma to hide the private symbols in bionic. It also lets the optimizer produce better and smaller machine code.

[PATCH android/bionic 1/3] Hide private symbols using GCC visibility pragma [PATCH android/bionic 2/3] Hide internal symbol __bionic_brk used by brk() and sbrk() [PATCH android/bionic 3/3] Hide libm private symbols using GCC visibility pragma