Fix HLE example in manual

Fix HLE example in manual

The HLE example in the manual only commits when using bool
for the flag, because __atomic_clear only writes bool, and
HLE requires the acquire and release to match.

So when the example is copied with e.g. an int variable it
does not commit and causes slower than expected performance.

Some people are running into problems because of this.

Switch it over to use __atomic_store.

Also fix a minor typo nearby.

gcc/:
2013-06-21  Andi Kleen  <ak@linux.intel.com>

	* doc/extend.texi: Dont use __atomic_clear in HLE
	example.  Fix typo.

git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@200304 138bc75d-0d04-0410-961f-82ee72b054a4