Remove lto bits from solaris makefile.

Change-Id: I5ff79fddce0140791e367fb44afffe3250574efa
There is no gb_Library_LTOFLAGS.

Change-Id: I3b6b18e45aaf88d1cc6038226f6984090163bdee
Tweak lto flags for gcc.

Change-Id: I490029f0727e060fdfdfc6e9adccd058b24e6b86
Remove hopefully now unneeded workaround for --enable-lto build.

Change-Id: Iaffcc0825415e6aee62029fbc380954449b8bcbf