Since __libc_start_main may not be in the same 256MB-aligned region as
the function __start, replace use of jal instruction with la/jalr.
This fixes linker issue reported in:
https://sourceware.org/bugzilla/show_bug.cgi?id=17601
[BZ #17601]
* sysdeps/mips/start.S (__start): Use indirect jump to call
__libc_start_main.