Fix the C library runtime initialization order.

Fix the C library runtime initialization order.

This allows libc.so to run the C runtime initializer as soon as the
dynamic linker loads the shared library, i.e. before any other initializers
(e.g. static C++ constructors in other shared libraries the executable depends
on).

This also removes the bug where the initializers from the executable itself
were run twice: once by the dynamic linker, and another time by __libc_init
as defined by libc_init_dynamic.c