Fix build with poppler-26.01.0.

Index: sdext/source/pdfimport/xpdfwrapper/pnghelper.cxx
--- sdext/source/pdfimport/xpdfwrapper/pnghelper.cxx.orig
+++ sdext/source/pdfimport/xpdfwrapper/pnghelper.cxx
@@ -215,7 +215,7 @@ void PngHelper::createPng( OutputBuffer&     o_rOutput
     aScanlines.reserve( nLineSize * height + height );
 
 #if POPPLER_CHECK_VERSION(25, 2, 0)
-    if (!str->reset())
+    if (!str->rewind())
         return;
 #else
     str->reset();
@@ -258,7 +258,7 @@ void PngHelper::createPng( OutputBuffer& o_rOutputBuf,
                         colorMap->getNumPixelComps(),
                         colorMap->getBits()));
 #if POPPLER_CHECK_VERSION(25, 2, 0)
-    if (!imgStr->reset())
+    if (!imgStr->rewind())
         return;
 #else
     imgStr->reset();
@@ -300,7 +300,7 @@ void PngHelper::createPng( OutputBuffer& o_rOutputBuf,
                         maskColorMap->getBits()));
 
 #if POPPLER_CHECK_VERSION(25, 2, 0)
-    if (!imgStrMask->reset())
+    if (!imgStrMask->rewind())
         return;
 #else
     imgStrMask->reset();
@@ -354,7 +354,7 @@ void PngHelper::createPng( OutputBuffer& o_rOutputBuf,
                         colorMap->getNumPixelComps(),
                         colorMap->getBits()));
 #if POPPLER_CHECK_VERSION(25, 2, 0)
-    if (!imgStr->reset())
+    if (!imgStr->rewind())
         return;
 #else
     imgStr->reset();
@@ -393,7 +393,7 @@ void PngHelper::createPng( OutputBuffer& o_rOutputBuf,
         new ImageStream(maskStr, maskWidth, 1, 1));
 
 #if POPPLER_CHECK_VERSION(25, 2, 0)
-    if (!imgStrMask->reset())
+    if (!imgStrMask->rewind())
         return;
 #else
     imgStrMask->reset();
