Configure: fixed detection of newer Apple clang compilers.

auto/cc/name

diff --git a/auto/cc/name b/auto/cc/name
index 7a5656c..51a7ed9 100644
--- a/auto/cc/name
+++ b/auto/cc/name
@@ -67,7 +67,7 @@
     NGX_CC_NAME=gcc
     echo " + using GNU C compiler"
 
-elif `$CC -v 2>&1 | grep 'clang version' >/dev/null 2>&1`; then
+elif `$CC -v 2>&1 | grep '\(clang\|LLVM\) version' >/dev/null 2>&1`; then
     NGX_CC_NAME=clang
     echo " + using Clang C compiler"