cmd/ld: fix syms that are both cgo_import_static & cgo_import_dynamic

This is needed for SWIG when linking in internal mode.  In
internal mode if a symbol was cgo_import_static we used to
forget that it was also cgo_import_dynamic.

R=rsc, r
CC=golang-dev
https://golang.org/cl/9080043

src/cmd/ld/go.c

@@ -463,11 +463,12 @@ loadcgo(char *file, char *pkg, char *p, int n)
 			s = lookup(local, 0);
 			if(local != f[1])
 				free(local);
-			if(s->type == 0 || s->type == SXREF) {
+			if(s->type == 0 || s->type == SXREF || s->type == SHOSTOBJ) {
 				s->dynimplib = lib;
 				s->extname = remote;
 				s->dynimpvers = q;
-				s->type = SDYNIMPORT;
+				if(s->type != SHOSTOBJ)
+					s->type = SDYNIMPORT;
 				havedynamic = 1;
 			}
 			continue;

src/cmd/ld/lib.c

@@ -331,8 +331,16 @@ loadlib(void)
 		// Drop all the cgo_import_static declarations.
 		// Turns out we won't be needing them.
 		for(s = allsym; s != S; s = s->allsym)
-			if(s->type == SHOSTOBJ)
-				s->type = 0;
+			if(s->type == SHOSTOBJ) {
+				// If a symbol was marked both
+				// cgo_import_static and cgo_import_dynamic,
+				// then we want to make it cgo_import_dynamic
+				// now.
+				if(s->extname != nil && s->cgoexport == 0) {
+					s->type = SDYNIMPORT;
+				} else
+					s->type = 0;
+			}
 	}
 	
 	// Now that we know the link mode, trim the dynexp list.