dri/common: use sysconfdir when looking for drirc

Useful when locally installed mesa has more quirks than the system one.

Signed-off-by: Marcin Ślusarz <marcin.slusarz@gmail.com>
Reviewed-by: Ilia Mirkin <imirkin@alum.mit.edu>
Reviewed-by: Emil Velikov <emil.l.velikov@gmail.com>

docs/autoconf.html

@@ -87,6 +87,13 @@ created in a <code>lib64</code> directory at the top of the Mesa source
 tree.</p>
 </dd>
 
+<dt><code>--sysconfdir=DIR</code></dt>
+<dd><p>This option specifies the directory where the configuration
+files will be installed. The default is <code>${prefix}/etc</code>.
+Currently there's only one config file provided when dri drivers are
+enabled - it's <code>drirc</code>.</p>
+</dd>
+
 <dt><code>--enable-static, --disable-shared</code></dt>
 <dd><p>By default, Mesa
 will build shared libraries. Either of these options will force static
@@ -217,7 +224,7 @@ GLX.
 <dt><code>--with-expat=DIR</code>
 <dd><p><strong>DEPRECATED</strong>, use <code>PKG_CONFIG_PATH</code> instead.</p>
 <p>The DRI-enabled libGL uses expat to
-parse the DRI configuration files in <code>/etc/drirc</code> and
+parse the DRI configuration files in <code>${sysconfdir}/drirc</code> and
 <code>~/.drirc</code>. This option allows a specific expat installation
 to be used. For example, <code>--with-expat=/usr/local</code> will
 search for expat headers and libraries in <code>/usr/local/include</code>

src/mesa/drivers/dri/common/Makefile.am

@@ -34,6 +34,7 @@ AM_CFLAGS = \
 	-I$(top_srcdir)/src/gallium/auxiliary \
 	$(LIBDRM_CFLAGS) \
 	$(DEFINES) \
+	-DSYSCONFDIR=\"$(sysconfdir)\"
 	$(VISIBILITY_CFLAGS)
 
 noinst_LTLIBRARIES = \

src/mesa/drivers/dri/common/xmlconfig.c

@@ -935,9 +935,13 @@ static void parseOneConfigFile (XML_Parser p) {
 #undef BUF_SIZE
 }
 
+#ifndef SYSCONFDIR
+#define SYSCONFDIR "/etc"
+#endif
+
 void driParseConfigFiles (driOptionCache *cache, const driOptionCache *info,
 			  int screenNum, const char *driverName) {
-    char *filenames[2] = {"/etc/drirc", NULL};
+    char *filenames[2] = { SYSCONFDIR "/drirc", NULL};
     char *home;
     uint32_t i;
     struct OptConfData userData;