+# Check for __attribute__((visibility()))
+AC_CACHE_CHECK([whether __attribute__((visibility())) is supported],
+ ac_cv_have_gnuc_visibility_attribute,
+ [cat > conftest.c <<EOF
+int foo __attribute__ ((visibility ("hidden"))) = 1;
+int bar __attribute__ ((visibility ("protected"))) = 1;
+EOF
+ ac_cv_have_gnuc_visibility_attribute="no"
+ if ${CC-cc} -Werror -S conftest.c -o conftest.s >/dev/null 2>&1; then
+ if grep '\.hidden.*foo' conftest.s >/dev/null; then
+ if grep '\.protected.*bar' conftest.s >/dev/null; then
+ ac_cv_have_gnuc_visibility_attribute="yes"
+ fi
+ fi
+ fi
+ rm -f conftest.[cs]
+])
+if test "$ac_cv_have_gnuc_visibility_attribute" = "yes"; then
+ AC_DEFINE([HAVE_GNUC_VISIBILITY_ATTRIBUTE], [1],
+ [Defined to 1 if GCC visibility attribute is supported])
+fi
+
+# Check for DRM (mandatory)