Fix many more comiler warnings

Most warnings were harmless, some real bugs. Test set should now compile
cleanly with ack, gcc, and clang.

test/test38.c

@@ -53,6 +53,8 @@ int main(int argc, char *argv[])
 	if (m & 0004) test38c();
   }
   quit();
+
+  return(-1);	/* Unreachable */
 }
 
 void test38a()