Add 'strcmp_collation' support for LC_COLLATE.

Add 'strcmp_collation' support for LC_COLLATE.

Support a new directive 'strcmp_collation' in the LC_COLLATE
section of a locale source file. This new directive causes all
collation rules to be dropped and instead 'strcmp' is used for
collation of the input character set. This is required to allow
for a C.UTF-8 that contains zero collation rules (minimal size)
and sorts using code point sorting.

Tested on x86_64 and i686 without regression.