--- configure.orig	2018-01-23 18:08:55 UTC
+++ configure
@@ -21895,12 +21895,13 @@ case "$host_os" in
 darwin*)
     ;;
 *)
-    for ac_func in clock_gettime
+    for ac_func in clock_gettime clock_nanosleep
 do :
-  ac_fn_c_check_func "$LINENO" "clock_gettime" "ac_cv_func_clock_gettime"
-if test "x$ac_cv_func_clock_gettime" = xyes; then :
+  as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
+ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"
+if eval test \"x\$"$as_ac_var"\" = x"yes"; then :
   cat >>confdefs.h <<_ACEOF
-#define HAVE_CLOCK_GETTIME 1
+#define `$as_echo "HAVE_$ac_func" | $as_tr_cpp` 1
 _ACEOF
  CLOCK_LIB=
 else
@@ -22559,11 +22559,20 @@ $as_echo "yes" >&6; }
 fi
 fi
 
-ac_fn_c_check_header_mongrel "$LINENO" "linux/futex.h" "ac_cv_header_linux_futex_h" "$ac_includes_default"
-if test "x$ac_cv_header_linux_futex_h" = xyes; then :
-  DEFINES="$DEFINES -DHAVE_LINUX_FUTEX_H"
+for ac_header in linux/futex.h sys/umtx.h
+do :
+  as_ac_Header=`$as_echo "ac_cv_header_$ac_header" | $as_tr_sh`
+ac_fn_c_check_header_compile "$LINENO" "$ac_header" "$as_ac_Header" "#include <errno.h>
+     #include <sys/types.h>
+"
+if eval test \"x\$"$as_ac_Header"\" = x"yes"; then :
+  cat >>confdefs.h <<_ACEOF
+#define `$as_echo "HAVE_$ac_header" | $as_tr_cpp` 1
+_ACEOF
+ DEFINES="$DEFINES -DHAVE_LINUX_FUTEX_H"
 fi
 
+done
 
 
 # Check whether --enable-selinux was given.
@@ -23308,7 +23308,7 @@ fi
 
 
 case "$host_os" in
-linux*)
+linux* | freebsd*)
     dri3_default=yes
     ;;
 *)
@@ -27096,9 +27106,6 @@ rm -f core conftest.err conftest.$ac_obj
         CLANG_LIBDIR=${LLVM_LIBDIR}
     fi
     CLANG_RESOURCE_DIR=$CLANG_LIBDIR/clang/${LLVM_VERSION}
-    if test ! -f "$CLANG_RESOURCE_DIR/include/stddef.h"; then :
-  as_fn_error $? "Could not find clang internal header stddef.h in $CLANG_RESOURCE_DIR Use --with-clang-libdir to specify the correct path to the clang libraries." "$LINENO" 5
-fi
 fi
  if test "x$enable_opencl" = xyes; then
   HAVE_CLOVER_TRUE=
