For libm, use a macro for aliasing symbols.

Change-Id: Ibd42ebc387c2bf3eba9aa96091770915b4b34184
diff --git a/libm/x86/s_expm1.S b/libm/x86/s_expm1.S
index 58819ef..1f21cde 100644
--- a/libm/x86/s_expm1.S
+++ b/libm/x86/s_expm1.S
@@ -365,8 +365,7 @@
 # -- End  expm1
 
 # Start file scope ASM
-.weak expm1l
-.equ expm1l, expm1
+ALIAS_SYMBOL(exmp1l, exmp1);
 # End file scope ASM
 	.section .rodata, "a"
 	.align 16