adding _0x macro for TAHOE.

adding _0x macro for TAHOE.

SCCS-vsn: lib/libm/common_source/acosh.c 1.4
SCCS-vsn: lib/libm/common_source/asinh.c 1.3
SCCS-vsn: lib/libm/common_source/cosh.c 1.5
SCCS-vsn: lib/libm/common_source/exp.c 1.7
SCCS-vsn: lib/libm/common_source/exp__E.c 1.5
SCCS-vsn: lib/libm/common_source/expm1.c 1.5
SCCS-vsn: lib/libm/common_source/floor.c 1.4
SCCS-vsn: lib/libm/common_source/log.c 1.5
SCCS-vsn: lib/libm/common_source/log10.c 1.4
SCCS-vsn: lib/libm/common_source/log1p.c 1.5
SCCS-vsn: lib/libm/common_source/log__L.c 1.4
SCCS-vsn: lib/libm/common_source/pow.c 1.5
SCCS-vsn: lib/libm/common_source/sinh.c 1.5