amo.h: New include file to provide ISA 3.0 atomic memory operation instruction support.

amo.h: New include file to provide ISA 3.0 atomic memory operation instruction support.

[gcc]
2017-10-09  Michael Meissner  <meissner@linux.vnet.ibm.com>

	* config/rs6000/amo.h: New include file to provide ISA 3.0 atomic
	memory operation instruction support.
	* config.gcc (powerpc*-*-*): Include amo.h as an extra header.
	(rs6000-ibm-aix[789]*): Likewise.
	* doc/extend.texi (PowerPC Atomic Memory Operation Functions):
	Document new functions.

[gcc/testsuite]
2017-10-09  Michael Meissner  <meissner@linux.vnet.ibm.com>

	* gcc.target/powerpc/amo1.c: New test.
	* gcc.target/powerpc/amo2.c: Likewise.

From-SVN: r253552