Support ldbl-opt libm_alias_double use from .S files.

Support ldbl-opt libm_alias_double use from .S files.

This patch makes the ldbl-opt libm_alias_double implementation support
use from .S sources, by adding a semicolon after its use of
weak_alias.

Tested (compilation only) with build-many-glibcs.py for
alpha-linux-gnu, in conjunction with a patch introducing uses of
libm_alias_double in alpha .S files.

	* sysdeps/ieee754/ldbl-opt/libm-alias-double.h
	(libm_alias_double_r): Add semicolon after weak_alias call.