make update_pch.sh abort on an error

The script depends also on generated sources in workdir, which
it may fail to find if they haven't been built before running
the script. Prefer to fail on errors rather than ignoring them.

Note that when using builddir != srcdir, the script requires
$WORKDIR to be set (done e.g. by the recommended
'make cmd cmd="./bin/update_pch.sh [..]"').

Change-Id: I93429c133bd0876730a850d944707880848201f0
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/113798
Tested-by: Jenkins
Reviewed-by: Luboš Luňák <l.lunak@collabora.com>

bin/update_pch

@@ -1107,7 +1107,8 @@ def main():
                         return 0
 
     # Didn't update.
-    return 1
+    # Use exit code 2 to distinguish it from exit code 1 used e.g. when an exception occurs.
+    return 2
 
 if __name__ == '__main__':
     """ Process all the includes in a Module

bin/update_pch.sh

@@ -58,6 +58,11 @@ for x in $headers; do
         libname=`echo $header | sed -e s/.*precompiled_// -e s/\.hxx//`
 
         ./bin/update_pch "$module" "$libname"
+        exitcode=$?
+        if test $exitcode -ne 0 -a $exitcode -ne 2; then
+            echo Failed.
+            exit 1
+        fi
     fi
 done