Remove more gcc warnings (gcc version dependent)

Author: tueda

sources/poly.cc

@@ -1997,7 +1997,7 @@ int poly::first_variable () const {
 
 	int var = AN.poly_num_vars;
 	for (int j=0; j<var; j++)
-		if (terms[2+j]>0) var=j;
+		if (terms[2+j]>0) return j;
 	return var;
 }
 

sources/pre.c

@@ -5248,6 +5248,7 @@ int DoExternal(UBYTE *s)
 			case 10:/*'\0' fits here*/
 				MesPrint("@Can't finde closing \"");
 				Terminate(-1);
+				break;
 			case 0:case 1: continue;
 			default:
 				break;
@@ -5629,6 +5630,7 @@ int DoFromExternal(UBYTE *s)
 			case 10:/*'\0' fits here*/
 				MesPrint("@Can't finde closing \"");
 				Terminate(-1);
+				break;
 			case 0:case 1: continue;
 			default:
 				break;

sources/startup.c

@@ -1042,7 +1042,7 @@ VOID StartVariables()
 	We do want to give them unique names though that the user cannot access.
 */
 	{
-		char dumstr[10];
+		char dumstr[20];
 		for ( ; i < FIRSTUSERSYMBOL; i++ ) {
 			sprintf(dumstr,":%d:",i);
 			AddSymbol((UBYTE *)dumstr,-MAXPOWER,MAXPOWER,VARTYPENONE,0);
@@ -1069,7 +1069,7 @@ VOID StartVariables()
 	We do want to give them unique names though that the user cannot access.
 */
 	{
-		char dumstr[10];
+		char dumstr[20];
 		for ( ; i < FIRSTUSERFUNCTION-FUNCTION; i++ ) {
 			sprintf(dumstr,"::%d::",i);
 			AddFunction((UBYTE *)dumstr,0,0,0,0,0,-1,-1);