autoconf: Introduce --with-clang-srcdir, to build out-of-tree clang as tools/clang on tools/Makefile.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@142102 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/configure b/configure
index 49e189a..c8b3c76 100755
--- a/configure
+++ b/configure
@@ -708,6 +708,7 @@
 OPTIMIZE_OPTION
 EXTRA_OPTIONS
 EXTRA_LD_OPTIONS
+CLANG_SRC_ROOT
 BINUTILS_INCDIR
 NM
 ifGNUmake
@@ -1433,6 +1434,7 @@
   --with-extra-ld-options Specify additional options to link LLVM with
   --with-ocaml-libdir     Specify install location for ocaml bindings (default
                           is stdlib)
+  --with-clang-srcdir     Directory to the out-of-tree Clang source
   --with-clang-resource-dir
                           Relative directory from the Clang binary for
                           resource files
@@ -5510,6 +5512,22 @@
 esac
 
 
+# Check whether --with-clang-srcdir was given.
+if test "${with_clang_srcdir+set}" = set; then
+  withval=$with_clang_srcdir;
+else
+  withval="-"
+fi
+
+case "$withval" in
+  -) clang_src_root="" ;;
+  /* | [A-Za-z]:[\\/]*) clang_src_root="$withval" ;;
+  *) clang_src_root="$ac_pwd/$withval" ;;
+esac
+CLANG_SRC_ROOT=$clang_src_root
+
+
+
 # Check whether --with-clang-resource-dir was given.
 if test "${with_clang_resource_dir+set}" = set; then
   withval=$with_clang_resource_dir;
@@ -10453,7 +10471,7 @@
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<EOF
-#line 10456 "configure"
+#line 10474 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -21906,6 +21924,7 @@
 OPTIMIZE_OPTION!$OPTIMIZE_OPTION$ac_delim
 EXTRA_OPTIONS!$EXTRA_OPTIONS$ac_delim
 EXTRA_LD_OPTIONS!$EXTRA_LD_OPTIONS$ac_delim
+CLANG_SRC_ROOT!$CLANG_SRC_ROOT$ac_delim
 BINUTILS_INCDIR!$BINUTILS_INCDIR$ac_delim
 NM!$NM$ac_delim
 ifGNUmake!$ifGNUmake$ac_delim
@@ -21987,7 +22006,7 @@
 LTLIBOBJS!$LTLIBOBJS$ac_delim
 _ACEOF
 
-  if test `sed -n "s/.*$ac_delim\$/X/p" conf$$subs.sed | grep -c X` = 88; then
+  if test `sed -n "s/.*$ac_delim\$/X/p" conf$$subs.sed | grep -c X` = 89; then
     break
   elif $ac_last_try; then
     { { echo "$as_me:$LINENO: error: could not make $CONFIG_STATUS" >&5