use _f007·filename for func literals.

this avoids problems people have run into with
multiple closures in the same package.

when preparing filename, only cut off .go, not .anything.
this fixes a bug tgs ran into with foo.pb.go and foo.go
in the same package.

also turn bad identifier chars from filename into
underscores: a-b.pb.go => a_b_pb

R=ken
OCL=27050
CL=27050

src/cmd/gc/dcl.c

@@ -583,7 +583,7 @@ funclit1(Type *type, Node *body)
 
 	// declare function.
 	vargen++;
-	snprint(namebuf, sizeof(namebuf), "_f%.3ld", vargen);
+	snprint(namebuf, sizeof(namebuf), "_f%.3ld·%s", vargen, filename);
 	f = newname(lookup(namebuf));
 	addvar(f, ft, PFUNC);
 	f->funcdepth = 0;

src/cmd/gc/lex.c

@@ -138,15 +138,23 @@ void
 setfilename(char *file)
 {
 	char *p;
+	int c;
 
 	p = strrchr(file, '/');
 	if(p != nil)
 		file = p+1;
 	strncpy(namebuf, file, sizeof(namebuf));
-	p = strchr(namebuf, '.');
-	if(p != nil)
+	p = strrchr(namebuf, '.');
+	if(p != nil && strcmp(p, ".go") == 0)
 		*p = 0;
 	filename = strdup(namebuf);
+	
+	// turn invalid identifier chars into _
+	for(p=filename; *p; p++) {
+		c = *p & 0xFF;
+		if(c < 0x80 && !isalpha(c) && !isdigit(c) && c != '_')
+			*p = '_';
+	}
 }
 
 int