For libm, use a macro for aliasing symbols.

Change-Id: Ibd42ebc387c2bf3eba9aa96091770915b4b34184
diff --git a/libm/x86/s_cos.S b/libm/x86/s_cos.S
index 0f5d570..fd5ef5d 100644
--- a/libm/x86/s_cos.S
+++ b/libm/x86/s_cos.S
@@ -314,8 +314,7 @@
 # -- End  cos
 
 # Start file scope ASM
-.weak cosl
-.equ cosl, cos
+ALIAS_SYMBOL(cosl, cos);
 # End file scope ASM
 	.section .rodata, "a"
 	.align 16