Fix for CONC-452 and CONC-453:

Various coverity scan fixes, including CONC-452 and CONC-453.
Special thanks to Lukas Javorsky for fixing numerous covscan
issues (This patch includes part of his pull request #126).

Coverity scan build was using the following cmake parameters:
-WITH_EXTERNAL_ZLIB=ON -DWITH_UNIT_TESTS=OFF.

CWE-416 (use after free) in dtoa.c (from netlib) is still open.

libmariadb/mariadb_rpl.c

@@ -387,12 +387,14 @@ MARIADB_RPL_EVENT * STDCALL mariadb_rpl_fetch(MARIADB_RPL *rpl, MARIADB_RPL_EVEN
       }
       break;
     default:
+      free(rpl_event);
       return NULL;
       break;
     }
     return rpl_event;
   }
 mem_error:
+  free(rpl_event);
   SET_CLIENT_ERROR(rpl->mysql, CR_OUT_OF_MEMORY, SQLSTATE_UNKNOWN, 0);
   return 0;
 }
@@ -458,6 +460,7 @@ int STDCALL mariadb_rpl_optionsv(MARIADB_RPL *rpl,
     goto end;
   }
 end:
+  va_end(ap);
   return rc;
 }
 
@@ -501,8 +504,10 @@ int STDCALL mariadb_rpl_get_optionsv(MARIADB_RPL *rpl,
     break;
   }
   default:
+    va_end(ap);
     return 1;
     break;
   }
+  va_end(ap);
   return 0;
 }