For libm, use a macro for aliasing symbols.

Change-Id: Ibd42ebc387c2bf3eba9aa96091770915b4b34184
diff --git a/libm/x86/s_tanh.S b/libm/x86/s_tanh.S
index 3975fa9..737bcbb 100644
--- a/libm/x86/s_tanh.S
+++ b/libm/x86/s_tanh.S
@@ -278,8 +278,7 @@
 # -- End  tanh
 
 # Start file scope ASM
-.weak tanhl
-.equ tanhl, tanh
+ALIAS_SYMBOL(tanhl, tanh);
 # End file scope ASM
 	.section .rodata, "a"
 	.align 16