Make sure we have an xref before using

KDE bug #335413 had this backtrace
XRef::getNumEntry (this=0x0, offset=-1) at XRef.cc:1300
0x00007f29aec1681e in Lexer::getObj (this=0x1648760, obj=obj@entry=0x1bdf978, cmdA=cmdA@entry=0x7f29aeca66c8 "endstream", objNum=objNum@entry=0) at Lexer.cc:594
0x00007f29aec20dfd in Parser::shift (this=this@entry=0x1bdf950, cmdA=cmdA@entry=0x7f29aeca66c8 "endstream", objNum=objNum@entry=0) at Parser.cc:323
0x00007f29aec20fde in Parser::makeStream (this=this@entry=0x1bdf950, dict=dict@entry=0x7fff2541cad0, fileKey=fileKey@entry=0x0, encAlgorithm=encAlgorithm@entry=cryptRC4, keyLength=keyLength@entry=0, objNum=objNum@entry=0, objGen=objGen@entry=0, recursion=recursion@entry=1, strict=strict@entry=false) at Parser.cc:245
0x00007f29aec216b8 in Parser::getObj (this=this@entry=0x1bdf950, obj=obj@entry=0x7fff2541cad0, simpleOnly=simpleOnly@entry=false, fileKey=fileKey@entry=0x0, encAlgorithm=encAlgorithm@entry=cryptRC4, keyLength=keyLength@entry=0, objNum=objNum@entry=0, objGen=objGen@entry=0, recursion=recursion@entry=0, strict=strict@entry=false) at Parser.cc:131
0x00007f29aec350fc in XRef::readXRef (this=this@entry=0xfe43a0, pos=pos@entry=0xfe4438, followedXRefStm=followedXRefStm@entry=0x7fff2541cb30, xrefStreamObjsNum=xrefStreamObjsNum@entry=0x0) at XRef.cc:551
0x00007f29aec35319 in XRef::XRef (this=0xfe43a0, strA=0x1c54ff0, pos=<optimized out>, mainXRefEntriesOffsetA=0, wasReconstructed=0x7fff2541cbaf, reconstruct=<optimized out>) at XRef.cc:342
0x00007f29aec2534f in PDFDoc::setup (this=this@entry=0x311e1b0, ownerPassword=ownerPassword@entry=0x1165830, userPassword=userPassword@entry=0x447f550) at PDFDoc.cc:262
Merge remote-tracking branch 'origin/poppler-0.26'
Update (C)
0.26.2
glib: fix typo in apidox
Add poppler-qt5.pc to .gitignore

https://bugs.freedesktop.org/show_bug.cgi?id=79744
Add test-driver to .gitignore

https://bugs.freedesktop.org/show_bug.cgi?id=79744
Add poppler-forms, stress-threads-qt, test-render-to-file to .gitignore

https://bugs.freedesktop.org/show_bug.cgi?id=79744
Add poppler-undeclared.txt to .gitignore

https://bugs.freedesktop.org/show_bug.cgi?id=79744
Add *.gir, *.typelib to glib/.gitignore

https://bugs.freedesktop.org/show_bug.cgi?id=79744
Add Changelog to .gitignore

https://bugs.freedesktop.org/show_bug.cgi?id=79744
Do not dist gir_DATA

See https://bugzilla.gnome.org/show_bug.cgi?id=621611 for rationale.
Increase required Qt4 version to 4.7.0

We use Qt::LayoutDirectionAuto, introduced in 4.7.0.

bug #81005
Merge remote-tracking branch 'origin/poppler-0.26'
Fix moc-qt5 detection

https://bugs.freedesktop.org/show_bug.cgi?id=80250
Merge remote-tracking branch 'origin/poppler-0.26'
Move automake version check from autogen.sh to configure.ac

https://bugs.freedesktop.org/show_bug.cgi?id=79797
Include stdio.h from poppler-config.h

In poppler-config.h there is a check for __MINGW_PRINTF_FORMAT,
which is set by stdio.h.

This fixes this warning when compling with the mingw-w64-compiler:

XRef.cc: In member function 'virtual void
XRef::XRefTableWriter::writeEntry(Goffset, int, XRefEntryType)':
XRef.cc:1460:94: warning: unknown conversion type character 'l' in format [-Wformat=]
    outStr->printf("%010lli %05i %c\r\n", (long long)offset, gen, (type==xrefEntryFree)?'f':'n');
^
XRef.cc:1460:94: warning: format '%i' expects argument of type 'int', but argument 3 has type 'Goffset {aka long long int}' [-Wformat=]
XRef.cc:1460:94: warning: too many arguments for format [-Wformat-extra-args]

https://bugs.freedesktop.org/show_bug.cgi?id=79762
Fix compilation of Qt5 frontend with MinGW
Add Hib's (C)