change from $$ to \n$$ for .6 meta section delimiter

R=r
DELTA=13  (5 added, 0 deleted, 8 changed)
OCL=18190
CL=18192

src/cmd/6l/go.c

@@ -91,14 +91,16 @@ ldpkg(Biobuf *f, int64 len, char *filename)
 		return;
 	}
 
-	// first $$ marks beginning of exports
-	p0 = strstr(data, "$$");
+	// first \n$$ marks beginning of exports - skip rest of line
+	p0 = strstr(data, "\n$$");
 	if(p0 == nil)
 		return;
-	p0 += 2;
+	p0 += 3;
 	while(*p0 != '\n' && *p0 != '\0')
 		p0++;
-	p1 = strstr(p0, "$$");
+
+	// second marks end of exports / beginning of local data
+	p1 = strstr(p0, "\n$$");
 	if(p1 == nil) {
 		fprint(2, "6l: cannot find end of exports in %s\n", filename);
 		return;
@@ -118,10 +120,13 @@ ldpkg(Biobuf *f, int64 len, char *filename)
 	loadpkgdata(filename, p0, p1 - p0);
 
 	// local types begin where exports end.
-	p0 = p1;
+	// skip rest of line after $$ we found above
+	p0 = p1 + 3;
 	while(*p0 != '\n' && *p0 != '\0')
 		p0++;
-	p1 = strstr(p0, "$$");
+
+	// local types end at next \n$$.
+	p1 = strstr(p0, "\n$$");
 	if(p1 == nil) {
 		fprint(2, "6l: cannot find end of local types in %s\n", filename);
 		return;

src/cmd/ar/ar.c

@@ -701,7 +701,7 @@ foundstart:
 			first = 0;
 			continue;
 		}
-		if (strstrn(line, Blinelen(b), "$$"))
+		if(line[0] == '$' && line[1] == '$')
 			goto foundend;
 		end = Boffset(b);  // before closing $$
 	}

src/cmd/gc/export.c

@@ -195,7 +195,7 @@ dumpexport(void)
 	lno = lineno;
 
 	Bprint(bout, "   import\n");
-	Bprint(bout, "   $$  // exports\n");
+	Bprint(bout, "\n$$  // exports\n");
 
 	Bprint(bout, "    package %s\n", package);