configure: use pkg-config to detect x11 and simplify checks

AC_PATH_XTRA macro unnecessarily pulls in libSM and libICE.

https://bugzilla.gnome.org/show_bug.cgi?id=731047

configure.ac

@@ -554,55 +554,28 @@ dnl Check for X11
 translit(dnm, m, l) AM_CONDITIONAL(USE_X, true)
 AG_GST_CHECK_FEATURE(X, [X libraries and plugins],
                   [ximagesrc], [
-  AG_GST_CHECK_X
-
-  if test "x$HAVE_X" = "xyes"
-  then
+  PKG_CHECK_MODULES(X, x11, [
     dnl check for Xfixes
-    PKG_CHECK_MODULES(XFIXES, xfixes, HAVE_XFIXES="yes", HAVE_XFIXES="no")
-    if test "x$HAVE_XFIXES" = "xyes"
-    then
-        XFIXES_CFLAGS="-DHAVE_XFIXES $XFIXES_CFLAGS"
-    fi
-    AC_SUBST(XFIXES_LIBS)
-    AC_SUBST(XFIXES_CFLAGS)
+    PKG_CHECK_MODULES(XFIXES, xfixes, [
+      AC_DEFINE(HAVE_XFIXES, 1, [Defined if Xfixes is available])
+    ])
 
     dnl check for Xdamage
-    PKG_CHECK_MODULES(XDAMAGE, xdamage, HAVE_XDAMAGE="yes", HAVE_XDAMAGE="no")
-    if test "x$HAVE_XDAMAGE" = "xyes"
-    then
-        XDAMAGE_CFLAGS="-DHAVE_XDAMAGE $XDAMAGE_CFLAGS"
-    fi
-    AC_SUBST(XDAMAGE_LIBS)
-    AC_SUBST(XDAMAGE_CFLAGS)
-  fi
-])
+    PKG_CHECK_MODULES(XDAMAGE, xdamage, [
+      AC_DEFINE(HAVE_XDAMAGE, 1, [Defined if Xdamage is available])
+    ])
 
-dnl FIXME: this should be rolled into the test above, it's just an additional
-dnl feature of the ximagesrc plug-in
-dnl This is the same as in gst-plugins-base
-dnl check for X Shm
-translit(dnm, m, l) AM_CONDITIONAL(USE_XSHM, true)
-AG_GST_CHECK_FEATURE(XSHM, [X Shared Memory extension], , [
-  if test x$HAVE_X = xyes; then
-    AC_CHECK_LIB(Xext, XShmAttach,
-                 HAVE_XSHM="yes", HAVE_XSHM="no",
-                 $X_LIBS)
-    if test "x$HAVE_XSHM" = "xyes"; then
-      XSHM_LIBS="-lXext"
-    else
-      dnl On AIX, it is in XextSam instead, but we still need -lXext
-      AC_CHECK_LIB(XextSam, XShmAttach,
-                   HAVE_XSHM="yes", HAVE_XSHM="no",
-                   $X_LIBS)
-      if test "x$HAVE_XSHM" = "xyes"; then
-        XSHM_LIBS="-lXext -lXextSam"
-      fi
-    fi
-  fi
-], ,[
-  AC_SUBST(HAVE_XSHM)
-  AC_SUBST(XSHM_LIBS)
+    dnl check for X Shm
+    PKG_CHECK_MODULES(XEXT, xext, [
+      AC_CHECK_LIB(Xext, XShmAttach, [
+        AC_DEFINE(HAVE_XSHM, 1, [Defined if XShm is available])
+        XSHM_LIBS="$XEXT_LIBS"
+        XSHM_CFLAGS="$XEXT_CFLAGS"
+      ], [ $X_LIBS ])
+    ])
+    AC_SUBST(XSHM_LIBS)
+    AC_SUBST(XSHM_CFLAGS)
+  ])
 ])
 
 dnl *** ext plug-ins ***
@@ -940,7 +913,6 @@ AM_CONDITIONAL(USE_VPX, false)
 AM_CONDITIONAL(USE_WAVEFORM, false)
 AM_CONDITIONAL(USE_WAVPACK, false)
 AM_CONDITIONAL(USE_X, false)
-AM_CONDITIONAL(USE_XSHM, false)
 AM_CONDITIONAL(USE_ZLIB, false)
 
 fi dnl of EXT plugins