Make cpp/poppler-version.h header optional

Older popler (SLE11) does not have this header yet.
With the code simply if the header not found define version to oldest
possible working candidate and also raise the .pc check to the same.

Change-Id: I039c879879188fe2eb90cd119b80a1d6354a6a9c
Reviewed-on: https://gerrit.libreoffice.org/15339Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

config_host/config_poppler.h.in

+/*
+Settings for poppler header file dection
+*/
+
+#ifndef CONFIG_POPPLER_H
+#define CONFIG_POPPLER_H
+
+#define HAVE_POPPLER_VERSION_H 0
+
+#endif

configure.ac

@@ -10434,14 +10434,15 @@ if test $_os != Android -a $_os != iOS -a \( -z "$enable_pdfimport" -o "$enable_
     if test "$with_system_poppler" = "yes"; then
         AC_MSG_RESULT([external])
         SYSTEM_POPPLER=TRUE
-        PKG_CHECK_MODULES( POPPLER, poppler >= 0.8.0 )
+        PKG_CHECK_MODULES( POPPLER, poppler >= 0.12.0 )
         AC_LANG_PUSH([C++])
         save_CXXFLAGS=$CXXFLAGS
         save_CPPFLAGS=$CPPFLAGS
         CXXFLAGS="$CXXFLAGS $POPPLER_CFLAGS"
         CPPFLAGS="$CPPFLAGS $POPPLER_CFLAGS"
-        AC_CHECK_HEADER([cpp/poppler-version.h], [],
-                   [AC_MSG_ERROR([cpp/poppler-version.h not found. Install poppler])], [])
+        AC_CHECK_HEADER([cpp/poppler-version.h],
+            [AC_DEFINE([HAVE_POPPLER_VERSION_H], 1)],
+            [])
         CXXFLAGS=$save_CXXFLAGS
         CPPFLAGS=$save_CPPFLAGS
         AC_LANG_POP([C++])
@@ -10451,6 +10452,7 @@ if test $_os != Android -a $_os != iOS -a \( -z "$enable_pdfimport" -o "$enable_
         AC_MSG_RESULT([internal])
         SYSTEM_POPPLER=
         BUILD_TYPE="$BUILD_TYPE POPPLER"
+        AC_DEFINE([HAVE_POPPLER_VERSION_H], 1)
     fi
 else
     AC_MSG_RESULT([no])
@@ -13004,6 +13006,7 @@ AC_CONFIG_HEADERS([config_host/config_vcl.h])
 AC_CONFIG_HEADERS([config_host/config_vclplug.h])
 AC_CONFIG_HEADERS([config_host/config_version.h])
 AC_CONFIG_HEADERS([config_host/config_oauth2.h])
+AC_CONFIG_HEADERS([config_host/config_poppler.h])
 AC_OUTPUT
 
 if test "$CROSS_COMPILING" = TRUE; then

sdext/source/pdfimport/xpdfwrapper/pdfioutdev_gpl.hxx

@@ -21,6 +21,7 @@
 #define INCLUDED_SDEXT_SOURCE_PDFIMPORT_XPDFWRAPPER_PDFIOUTDEV_GPL_HXX
 
 #include <sal/types.h>
+#include <config_poppler.h>
 
 #if defined __GNUC__
 # pragma GCC diagnostic push
@@ -50,7 +51,14 @@
 class GfxPath;
 class GfxFont;
 class PDFDoc;
+#if HAVE_POPPLER_VERSION_H
 #include <cpp/poppler-version.h>
+#else
+#define POPPLER_VERSION "0.12.3"
+#define POPPLER_VERSION_MAJOR 0
+#define POPPLER_VERSION_MINOR 12
+#define POPPLER_VERSION_MICRO 3
+#endif
 #define POPPLER_CHECK_VERSION(major,minor,micro) \
   (POPPLER_VERSION_MAJOR > (major) || \
    (POPPLER_VERSION_MAJOR == (major) && POPPLER_VERSION_MINOR > (minor)) || \