autoconf: Error for incompatible version of libdrm

The DRI modules can only be built against libdrm master (currently
version 2.3.1), so this should be enforced to save people from trying to
build against older versions.

Added a section at the top of the script to consolidate all required
versions.

diff --git a/configure.ac b/configure.ac
index ca63c7e20af0d386f1b3581895012a2727616f65..bc2ebf6583f8c9a60be455981588bb1d50689583 100644 (file)
--- a/configure.ac
+++ b/configure.ac
@@ -17,6 +17,10 @@ AC_INIT([Mesa],[mesa_version],
 AC_CONFIG_AUX_DIR([bin])
 AC_CANONICAL_HOST
 
+dnl Versions for external dependencies
+LIBDRM_REQUIRED=2.3.1
+DRI2PROTO_REQUIRED=1.1
+
 dnl Check for progs
 AC_PROG_CPP
 AC_PROG_CC
@@ -404,8 +408,8 @@ dri)
     fi
 
     # Check for libdrm
-    PKG_CHECK_MODULES([LIBDRM], [libdrm])
-    PKG_CHECK_MODULES([DRI2PROTO], [dri2proto >= 1.1])
+    PKG_CHECK_MODULES([LIBDRM], [libdrm >= $LIBDRM_REQUIRED])
+    PKG_CHECK_MODULES([DRI2PROTO], [dri2proto >= $DRI2PROTO_REQUIRED])
 
     # find the DRI deps for libGL
     if test "$x11_pkgconfig" = yes; then