Fix two compiler warnings. No functional code changes.

FossilOrigin-Name: c829868aa2254c5e2268cdb803462cc6ec5cb71e

src/os_unix.c

@@ -1357,6 +1357,7 @@ static int _posixUnlock(sqlite3_file *id, int eFileLock, int handleNFSUnlock){
     if( eFileLock==SHARED_LOCK ){
 
 #if !defined(__APPLE__) || !SQLITE_ENABLE_LOCKING_STYLE
+      (void)handleNFSUnlock;
       assert( handleNFSUnlock==0 );
 #endif
 #if defined(__APPLE__) && SQLITE_ENABLE_LOCKING_STYLE

src/util.c

@@ -1145,6 +1145,6 @@ int sqlite3MulInt64(i64 *pA, i64 iB){
 */
 int sqlite3AbsInt32(int x){
   if( x>=0 ) return x;
-  if( x==0x80000000 ) return 0x7fffffff;
+  if( x==(int)0x80000000 ) return 0x7fffffff;
   return -x;
 }