Crazy replacement for strong_alias on macOS.

This was cobbled together from a few different references.
All it's doing is forcing a symbol to be created with the slurm_*
name, and setting the symbol address to that of the unaliased symbol.

src/common/macros.h

@@ -380,10 +380,10 @@
 #    define strong_alias(name, aliasname) \
      extern __typeof (name) aliasname __attribute ((alias (#name)))
 #  else
-     /* dummy function definition,
-      * confirm "aliasname" is free and waste "name" */
 #    define strong_alias(name, aliasname) \
-     extern void aliasname(int name)
+     __asm__(".global _" #aliasname); \
+     __asm__(".set _" #aliasname ", _" #name); \
+     extern __typeof (name) aliasname
 #  endif
 #endif