gpg4libre: Support building --with-system-gpgme (Linux only so far)

Change-Id: I22af89b920d43f3fc5f0fff02070f288bfa59fb4
Reviewed-on: https://gerrit.libreoffice.org/33702Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Siegmund Gorr <siegmund.gorr@cib.de>
Reviewed-by: Thorsten Behrens <Thorsten.Behrens@CIB.de>

RepositoryExternal.mk

@@ -3423,6 +3423,22 @@ endef
 
 endif # ENABLE_BREAKPAD
 
+ifneq ($(SYSTEM_GPGME),)
+
+define gb_LinkTarget__use_gpgme
+$(call gb_LinkTarget_set_include,$(1),\
+	$$(INCLUDE) \
+	$$(GPGME_CFLAGS) \
+)
+
+$(call gb_LinkTarget_add_libs,$(1),\
+    $(GPGME_LIBS) \
+)
+
+endef
+
+endif
+
 ifeq ($(ENABLE_GLTF),TRUE)
 
 ifneq ($(SYSTEM_LIBGLTF),TRUE)

config_host.mk.in

@@ -203,6 +203,8 @@ export GIT_NEEDED_SUBMODULES=@GIT_NEEDED_SUBMODULES@
 export EPOXY_CFLAGS=$(gb_SPACE)@EPOXY_CFLAGS@
 export EPOXY_LIBS=$(gb_SPACE)@EPOXY_LIBS@
 export GLM_CFLAGS=$(gb_SPACE)@GLM_CFLAGS@
+export GPGME_CFLAGS=$(gb_SPACE)@GPGME_CFLAGS@
+export GPGME_LIBS=$(gb_SPACE)@GPGME_LIBS@
 export GNOMEVFS_CFLAGS=$(gb_SPACE)@GNOMEVFS_CFLAGS@
 export GNOMEVFS_LIBS=$(gb_SPACE)@GNOMEVFS_LIBS@
 export GNUTLS_CFLAGS=$(gb_SPACE)@GNUTLS_CFLAGS@
@@ -516,6 +518,7 @@ export SYSTEM_GENCCODE=@SYSTEM_GENCCODE@
 export SYSTEM_GENCMN=@SYSTEM_GENCMN@
 export SYSTEM_EPOXY=@SYSTEM_EPOXY@
 export SYSTEM_GLM=@SYSTEM_GLM@
+export SYSTEM_GPGME=@SYSTEM_GPGME@
 export SYSTEM_GRAPHITE=@SYSTEM_GRAPHITE@
 export SYSTEM_HARFBUZZ=@SYSTEM_HARFBUZZ@
 export SYSTEM_HSQLDB=@SYSTEM_HSQLDB@

configure.ac

@@ -1721,6 +1721,11 @@ AC_ARG_WITH(system-poppler,
         [Use system poppler (only needed for PDF import).]),,
     [with_system_poppler="$with_system_libs"])
 
+AC_ARG_WITH(system-gpgme,
+    AS_HELP_STRING([--with-system-gpgme],
+        [Use gpgme already on system]),,
+    [with_system_gpgme="$with_system_libs"])
+
 AC_ARG_WITH(system-apache-commons,
     AS_HELP_STRING([--with-system-apache-commons],
         [Use Apache commons libraries already on system.]),,
@@ -10622,6 +10627,29 @@ AC_SUBST(SYSTEM_POPPLER)
 AC_SUBST(POPPLER_CFLAGS)
 AC_SUBST(POPPLER_LIBS)
 
+SYSTEM_GPGME=
+if test "$_os" = "Linux"; then
+    dnl ===================================================================
+    dnl Check for system gpgme
+    dnl ===================================================================
+    AC_MSG_CHECKING([which gpgme to use])
+    if test "$with_system_gpgme" = "yes"; then
+        AC_MSG_RESULT([external])
+        SYSTEM_GPGME=TRUE
+
+        AC_PATH_PROG(GPGMECONFIG, gpgme-config)
+        if test -z "$GPGMECONFIG"; then
+            AC_MSG_ERROR([--with-system-gpgme requested, but gpgme programs not found])
+        fi
+
+        GPGME_CFLAGS=`$GPGMECONFIG --cflags`
+        GPGME_LIBS=`$GPGMECONFIG --libs`
+    fi
+fi
+AC_SUBST(SYSTEM_GPGME)
+AC_SUBST(GPGME_CFLAGS)
+AC_SUBST(GPGME_LIBS)
+
 AC_MSG_CHECKING([whether to build the Wiki Publisher extension])
 if test "x$enable_ext_wiki_publisher" = "xyes" -a "x$enable_extension_integration" != "xno" -a "$with_java" != "no"; then
     AC_MSG_RESULT([yes])