avoid hang in short pbm

Change-Id: I9b7f0832a4dc231e1e8f963858c155e3cd392667
(cherry picked from commit b8637e67)
Reviewed-on: https://gerrit.libreoffice.org/17083Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Michael Meeks <michael.meeks@collabora.com>

filter/qa/cppunit/data/pbm/indeterminate/.gitignore

+*.ppm-*

filter/qa/cppunit/filters-ppm-test.cxx

@@ -62,6 +62,10 @@ void PpmFilterTest::testCVEs()
     testDir(OUString(),
         getURLFromSrc("/filter/qa/cppunit/data/ppm/"),
         OUString());
+
+    testDir(OUString(),
+        getURLFromSrc("/filter/qa/cppunit/data/pbm/"),
+        OUString());
 }
 
 CPPUNIT_TEST_SUITE_REGISTRATION(PpmFilterTest);

filter/source/graphicfilter/ipbm/ipbm.cxx

@@ -179,7 +179,7 @@ bool PBMReader::ImplReadHeader()
     }
     while ( !bFinished )
     {
-        if ( mrPBM.GetError() )
+        if (!mrPBM.good())
             return false;
 
         mrPBM.ReadUChar( nDat );