Add 'const' qualifiers where needed to avoid compiler warnings.

* libltp/lib/tst_sig.c (tst_sig): Don't attempt to cleanup on
fatal errors.
* libltp/lib/parse_opts.c (parse_opts): Initialize allocated
string to prevent heap corruption.

winsup/testsuite/libltp/lib/tst_sig.c

@@ -150,7 +150,15 @@ tst_sig(int fork_flag, void (*handler)(), void (*cleanup)())
 #ifdef SIGPTRESCHED
                 case SIGPTRESCHED:
 #endif /* SIGPTRESCHED */
-
+#ifdef __CYGWIN__
+		case SIGSEGV:
+		case SIGILL:
+		case SIGTRAP:
+		case SIGABRT:
+		case SIGEMT:
+		case SIGFPE:
+		case SIGBUS:
+#endif
 	            break;
 
 	        case SIGCLD: