Use parentheses around `&&` withing `||`

While the current form is perfectly valid, using parentheses around `&&`
would prevent future errors when modifiying the expression.

argtable3.c

@@ -3412,10 +3412,10 @@ static const TRexChar *trex_matchnode(TRex* exp,TRexNode *node,const TRexChar *s
 			return cur;
 	}
 	case OP_WB:
-		if(str == exp->_bol && !isspace(*str)
-		 || (str == exp->_eol && !isspace(*(str-1)))
-		 || (!isspace(*str) && isspace(*(str+1)))
-		 || (isspace(*str) && !isspace(*(str+1))) ) {
+		if((str == exp->_bol && !isspace(*str))
+		 || ((str == exp->_eol && !isspace(*(str-1))))
+		 || ((!isspace(*str) && isspace(*(str+1))))
+		 || ((isspace(*str) && !isspace(*(str+1)))) ) {
 			return (node->left == 'b')?str:NULL;
 		}
 		return (node->left == 'b')?NULL:str;