Fuzz builds ok (#1007)

* Fuzzing M68K without abort

* UC_MODE_32 is not ok with sparc

use UC_MODE_SPARC32|UC_MODE_BIG_ENDIAN instead

* Temporary removing leaking on start targets

* Do not abort for m68K undef instructions

tests/regress/memleak_sparc.c

@@ -55,7 +55,7 @@ static void test_sparc(void)
     printf("Emulate SPARC code\n");
 
     // Initialize emulator in Sparc mode
-    err = uc_open(UC_ARCH_SPARC, UC_MODE_32, &uc);
+    err = uc_open(UC_ARCH_SPARC, UC_MODE_SPARC32|UC_MODE_BIG_ENDIAN, &uc);
     if (err) {
         printf("Failed on uc_open() with error returned: %u (%s)\n",
                 err, uc_strerror(err));