pgsql: Fix a few problems in barrier.h.

Fix a few problems in barrier.h.

On HPPA, implement pg_memory_barrier() as pg_compiler_barrier(), which
should be correct since this arch doesn't do memory access reordering,
and is anyway better than the completely-nonfunctional-on-this-arch
dummy_spinlock code. (But note this patch only fixes things for gcc,
not for builds with HP's compiler.)

Also, fix incorrect default definition of pg_memory_barrier as a macro
requiring an argument.

Also, fix incorrect spelling of "#elif" as "#else if" in icc code path
(spotted by pgindent).

This doesn't come close to fixing all of the functional and stylistic
deficiencies in barrier.h, but at least it un-breaks my personal build.
Now that we're actually using barriers in the code, this file is going
to need some serious attention.

Branch
------
master

Details
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http://git.postgresql.org/pg/commitdiff/89779bf2c8f9aa480e0ceb8883f93e9d65c43a6e

Modified Files
--------------
src/include/storage/barrier.h | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)