[totem-pl-parser] build: Allow detecting the GMime API we are building against

[Bastien Nocera <hadess src gnome org>]

commit 972138e113efa9971cba2bb9c13d5656af68226c
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Thu Apr 13 10:50:49 2017 +0100

    build: Allow detecting the GMime API we are building against
    
    Since we support GMime 2.6 and 3.0, and there are going to be API
    differences between the two, we will need a way to check which version
    of GMime we are building against from inside the code.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=781254

 configure.ac |   14 +++++++++-----
 1 files changed, 9 insertions(+), 5 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index 410051f..3ba841f 100644
--- a/configure.ac
+++ b/configure.ac
@@ -83,15 +83,16 @@ AC_ARG_ENABLE(gmime-i-know-what-im-doing,
                             [enable_gmime=yes])
 
 if test "x$enable_gmime" = "xyes" ; then
-   PKG_CHECK_MODULES(GMIME,  
-                      gmime-2.6,
-                      [have_gmime=yes GMIME=gmime-2.6], 
-                      [have_gmime=no])
+   have_gmime3=no
+   PKG_CHECK_MODULES(GMIME,
+                     gmime-2.6,
+                     [have_gmime=yes GMIME=gmime-2.6],
+                     [have_gmime=no])
 
    if test "x$have_gmime" = "xno" ; then
        PKG_CHECK_MODULES(GMIME,
                          gmime-3.0,
-                         [have_gmime=yes GMIME=gmime-3.0],
+                         [have_gmime=yes have_gmime3=yes GMIME=gmime-3.0],
                          [have_gmime=no])
    fi
 
@@ -99,6 +100,9 @@ if test "x$enable_gmime" = "xyes" ; then
       AC_SUBST(GMIME, $GMIME)
       AC_SUBST(USEGMIME, yes)
       AC_DEFINE(HAVE_GMIME, 1, [GMime available in the system])
+      if test "x$have_gmime3" = xyes ; then
+        AC_DEFINE(HAVE_GMIME3, 1, [GMime 3.0 available in the system])
+      fi
       pkg_modules="$pkg_modules $GMIME"
    else
       AC_MSG_ERROR([libgmime is required to compile totem-pl-parser.])