For libm, use a macro for aliasing symbols.

Change-Id: Ibd42ebc387c2bf3eba9aa96091770915b4b34184
diff --git a/libm/x86/s_atan.S b/libm/x86/s_atan.S
index 67d8c02..c4413f1 100644
--- a/libm/x86/s_atan.S
+++ b/libm/x86/s_atan.S
@@ -245,8 +245,7 @@
 # -- End  atan
 
 # Start file scope ASM
-.weak atanl
-.equ atanl, atan
+ALIAS_SYMBOL(atanl, atan);
 # End file scope ASM
 	.section .rodata, "a"
 	.align 16