tests: add a few try/catch in main to shut coverity up

tests/hash-target.cpp

@@ -32,6 +32,7 @@
 #include <cstdlib>
 #include <cstring>
 #include <limits>
+#include "misc_log_ex.h"
 #include "crypto/hash.h"
 #include "cryptonote_basic/difficulty.h"
 
@@ -39,6 +40,7 @@ using namespace std;
 using cryptonote::check_hash;
 
 int main(int argc, char *argv[]) {
+  TRY_ENTRY();
   crypto::hash h;
   for (cryptonote::difficulty_type diff = 1;; diff += 1 + (diff >> 8)) {
     for (uint16_t b = 0; b < 256; b++) {
@@ -83,4 +85,5 @@ int main(int argc, char *argv[]) {
     }
   }
   return 0;
+  CATCH_ENTRY_L0("main", 1);
 }