Gustavo Romero authored Mar 26, 2017 and Jakub Jirutka committed Mar 26, 2017

Remove dependency on glibc by using gcc builtin function and no glibc
wrappers.

Currently there are no surrogates in musl for:

  __ppc_get_timebase()
  __ppc_set_ppr_low()
  __ppc_set_ppr_med()

however glibc __ppc_get_timebase() is just a wrapper for GCC builtin
__builtin_get_timebase() available since GCC 4.8 [1], so assuming that
aports on ppc64le will never be built using GCC < 4.8 we can just
switch directly to the GCC builtin function.

Also __ppc_set_ppr_{low,med}() are not available on musl but both
are simple glibc wrappers on a single asm instruction, hence there
is no harm in using asm directly instead. Actually, using asm
directly was the first solution adopted in MariaDB [2].

[1] https://goo.gl/jxLV6O
[2] https://goo.gl/9bjuVC