[evince] build: Use synctex system library if available

[Germán Poo-Caamaño <gpoo src gnome org>]

commit 9edaca5b7b35bbbeeecfaf8d9291a4c092d8be91
Author: Germán Poo-Caamaño <gpoo gnome org>
Date:   Fri May 18 22:13:19 2018 -0400

    build: Use synctex system library if available
    
    Check if a system synctex is available and use that instead of
    bundled version if possible.
    
    Fixes #479

 configure.ac            | 14 ++++++++++++++
 cut-n-paste/Makefile.am |  6 +++++-
 libdocument/Makefile.am |  4 ++--
 3 files changed, 21 insertions(+), 3 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 0f7bc62a..4f93bf43 100644
--- a/configure.ac
+++ b/configure.ac
@@ -536,6 +536,19 @@ fi
 
 GOBJECT_INTROSPECTION_CHECK([1.0])
 
+dnl ================== libsynctex ===========================================
+
+PKG_CHECK_MODULES(SYNCTEX, [synctex], has_synctex=system, has_synctex=internal)
+
+dnl not found? use internal code copy.
+if test "x$has_synctex" = "xinternal"; then
+       SYNCTEX_LIBS="\$(top_builddir)/cut-n-paste/synctex/libsynctex.la"
+       SYNCTEX_CFLAGS="-I\$(top_srcdir)/cut-n-paste/synctex"
+fi
+AC_SUBST(SYNCTEX_LIBS)
+AC_SUBST(SYNCTEX_CFLAGS)
+AM_CONDITIONAL(USE_INTERNAL_SYNCTEX, test x$has_synctex = xinternal)
+
 dnl ================== portability checks ===========================================
 
 dnl for backtrace()
@@ -1033,4 +1046,5 @@ GTK+ Unix Print ..........:  $with_gtk_unix_print
 Thumbnail cache ..........:  $enable_gnome_desktop
 Multimedia ...............:  $enable_multimedia
 Spell Checker.............:  $with_gspell
+SyncTeX ..................:  $has_synctex
 ])
diff --git a/cut-n-paste/Makefile.am b/cut-n-paste/Makefile.am
index a049b7fd..039f3aa1 100644
--- a/cut-n-paste/Makefile.am
+++ b/cut-n-paste/Makefile.am
@@ -1,3 +1,7 @@
-SUBDIRS = gimpcellrenderertoggle synctex libgd unarr
+SUBDIRS = gimpcellrenderertoggle libgd unarr
+
+if USE_INTERNAL_SYNCTEX
+SUBDIRS += synctex
+endif
 
 -include $(top_srcdir)/git.mk
diff --git a/libdocument/Makefile.am b/libdocument/Makefile.am
index 32bdfaa4..46cdee4e 100644
--- a/libdocument/Makefile.am
+++ b/libdocument/Makefile.am
@@ -107,7 +107,7 @@ libevdocument3_la_CPPFLAGS = \
 
 libevdocument3_la_CFLAGS = \
        $(LIBDOCUMENT_CFLAGS)                   \
-       -I$(top_srcdir)/cut-n-paste/synctex     \
+       $(SYNCTEX_CFLAGS) \
        $(AM_CFLAGS)
 
 libevdocument3_la_LDFLAGS = \
@@ -117,7 +117,7 @@ libevdocument3_la_LDFLAGS = \
        $(AM_LDFLAGS)
 
 libevdocument3_la_LIBADD = \
-       $(top_builddir)/cut-n-paste/synctex/libsynctex.la \
+       $(SYNCTEX_LIBS) \
        $(LIBDOCUMENT_LIBS)     \
        $(ZLIB_LIBS)            \
        $(LIBM)