In order to allow the unwinder code to have meaningful names for
libc functions, leave the symbol table. This results in the libc.so
getting to be about ~130K larger on all arm platforms and about ~70K
larger on mips/x86 platforms.
Bug: 12958251
Change-Id: I6b3a97e4824142faf5de46aeabf7c1dfb98a8cc6