For libm, use a macro for aliasing symbols.

Change-Id: Ibd42ebc387c2bf3eba9aa96091770915b4b34184
diff --git a/libm/x86/e_exp.S b/libm/x86/e_exp.S
index c4fbe47..eab619d 100644
--- a/libm/x86/e_exp.S
+++ b/libm/x86/e_exp.S
@@ -257,8 +257,7 @@
 # -- End  exp
 
 # Start file scope ASM
-.weak expl
-.equ expl, exp
+ALIAS_SYMBOL(expl, exp);
 # End file scope ASM
 	.section .rodata, "a"
 	.align 16