macos: Fix asm-c-connect-test

via some heavy-handed hackery in the ASM symbol handling in case
C symbols get a leading underscore (but ASM symbols do not).
But this is now like clang and GCC on Darwin work: asm symbols are
undecorated, C symbols get a _ prepended, so to connect both some
trickery is involved for the ASM symbols that don't have a _ prepended.
They must be included in the C symbol table (because that's what we use
to lookup also ASM labels), but they also must not disturb the normal
C symbol (which don't have the _ prepended), so they need some mangling.

A bit unsatisfying, but well.  So, add asm-c-connect-test to the working
ones for Darwin as well.

tests/tests2/85_asm-outside-function.c

@@ -1,6 +1,11 @@
+#ifdef __APPLE__
+#define _ "_"
+#else
+#define _
+#endif
 extern int printf (const char *, ...);
 extern void vide(void);
-__asm__("vide: ret");
+__asm__(_"vide: ret");
 
 int main() {
     vide();