Bump glibc

tools/linuxdeployqt/main.cpp

@@ -193,10 +193,12 @@ int main(int argc, char **argv)
         qInfo() << "         https://github.com/probonopd/linuxdeployqt/issues/340";
      } else {
         // openSUSE Leap 15.0 uses glibc 2.26 and is used on OBS
-        if (strverscmp (glcv, "2.27") >= 0) {
+        // Ubuntu Xenial (16.04) uses glibc 2.23
+        // Ubuntu Bionic (18.04) uses glibc 2.27
+        if (strverscmp (glcv, "2.28") >= 0) {
             qInfo() << "ERROR: The host system is too new.";
             qInfo() << "Please run on a system with a glibc version no newer than what comes with the oldest";
-            qInfo() << "currently still-supported mainstream distribution (xenial), which is glibc 2.23.";
+            qInfo() << "currently still-supported mainstream distribution (Ubuntu Bionic), which is glibc 2.27.";
             qInfo() << "This is so that the resulting bundle will work on most still-supported Linux distributions.";
             qInfo() << "For more information, please see";
             qInfo() << "https://github.com/probonopd/linuxdeployqt/issues/340";