Fix build against xorg-server >= 1.20.

Patch taken from upstream:
https://cgit.freedesktop.org/xorg/driver/xf86-video-savage/commit/?id=0ece556daa8a88771b669d8104396abd9166d2d0

diff --git a/src/savage_driver.c b/src/savage_driver.c
index 58a294d..3cda923 100644
--- a/src/savage_driver.c
+++ b/src/savage_driver.c
@@ -2034,8 +2034,6 @@ static Bool SavagePreInit(ScrnInfoPtr pScrn, int flags)
     xf86DrvMsg(pScrn->scrnIndex, X_PROBED, "Detected current MCLK value of %1.3f MHz\n",
 	       mclk / 1000.0);
 
-    pScrn->maxHValue = 2048 << 3;	/* 11 bits of h_total 8-pixel units */
-    pScrn->maxVValue = 2048;		/* 11 bits of v_total */
     pScrn->virtualX = pScrn->display->virtualX;
     pScrn->virtualY = pScrn->display->virtualY;
 
@@ -3637,6 +3635,14 @@ static ModeStatus SavageValidMode(SCRN_ARG_TYPE arg, DisplayModePtr pMode,
        (pMode->VDisplay > psav->PanelY)))
 	    return MODE_PANEL;
 
+    /* 11 bits of h_total 8-pixel units */
+    if (pMode->HTotal > (2048 << 3))
+	return MODE_BAD_HVALUE;
+
+    /* 11 bits of v_total */
+    if (pMode->VTotal > 2048)
+	return MODE_BAD_VVALUE;
+
     if (psav->UseBIOS) {
 	refresh = SavageGetRefresh(pMode);
         return (SavageMatchBiosMode(pScrn,pMode->HDisplay,
ix/tree/tests/gnu-maintenance.scm?id=ed0a3bea35fc8593724565c18f3ac0d107eb28d4'>tree</a><a href='/guix/commit/tests/gnu-maintenance.scm?id=ed0a3bea35fc8593724565c18f3ac0d107eb28d4'>commit</a><a href='/guix/diff/tests/gnu-maintenance.scm?id=ed0a3bea35fc8593724565c18f3ac0d107eb28d4'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/tests/gnu-maintenance.scm'>
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<tr><td><span title='2016-04-03 14:19:09 +0200'>2016-04-03</span></td><td><a href='/guix/commit/tests/gnu-maintenance.scm?id=a9edb211e733b8b34e67ec3b4450567e9376986f'>build: Add a Guile custom test driver using SRFI-64.</a><span class='msg-avail'>...<span class='msg-tooltip'>Before that '.log' files for scheme tests were fragmented and not
included in test-suite.log.  This unifies the semantics of SRFI-64 API
with Automake test suite.

* build-aux/test-driver.scm: New file.
* Makefile.am (SCM_LOG_DRIVER, AM_SCM_LOG_DRIVER_FLAGS): New variables.
(SCM_LOG_COMPILER, AM_SCM_LOG_FLAGS): Delete variables.
(AM_TESTS_ENVIRONMENT): Set GUILE_AUTO_COMPILE to 0.
* test-env.in: Silence guix-daemon.
* doc/guix.texi (Running the Test Suite): Describe how to display the
detailed results.  Bug reports require only 'test-suite.log' file.
* tests/base32.scm, tests/build-utils.scm, tests/builders.scm,
tests/challenge.scm, tests/cpan.scm, tests/cpio.scm, tests/cran.scm,
tests/cve.scm, tests/derivations.scm, tests/elpa.scm,
tests/file-systems.scm, tests/gem.scm, tests/gexp.scm,
tests/gnu-maintenance.scm, tests/grafts.scm, tests/graph.scm,
tests/gremlin.scm, tests/hackage.scm, tests/hash.scm,
tests/import-utils.scm, tests/lint.scm, tests/monads.scm, tests/nar.scm,
tests/packages.scm, tests/pk-crypto.scm, tests/pki.scm,
tests/profiles.scm, tests/publish.scm, tests/pypi.scm,
tests/records.scm, tests/scripts-build.scm, tests/scripts.scm,
tests/services.scm, tests/sets.scm, tests/size.scm, tests/snix.scm,
tests/store.scm, tests/substitute.scm, tests/syscalls.scm,
tests/system.scm, tests/ui.scm, tests/union.scm, tests/upstream.scm,
tests/utils.scm: Don't exit at the end of test groups.
* tests/containers.scm: Likewise.  Use 'test-skip' instead of exiting
with error code 77.
</span></span></td><td>Mathieu Lirzin</td></tr>
<tr><td><span title='2015-12-07 23:32:01 +0100'>2015-12-07</span></td><td><a href='/guix/commit/tests/gnu-maintenance.scm?id=202440e07a9dd40dc4b9814a91c67e24554d53c1'>gnu-maintenance: Add tests for 'release-file?'.</a><span class='msg-avail'>...<span class='msg-tooltip'>* tests/gnu-maintenance.scm: New file.
* Makefile.am (SCM_TESTS): Add it.
* guix/gnu-maintenance.scm (release-file?): Export.
</span></span></td><td>Ludovic Courtès</td></tr>