Configure: additional test for ExtUtils::Embed perl module presence.

Now perl configure will correctly fail if ExtUtils::Embed perl module
is not present in the system (found on Amazon Linux AMI, as of
release 2012.03).

auto/lib/perl/conf

diff --git a/auto/lib/perl/conf b/auto/lib/perl/conf
index 52c7084..5ce6c91 100644
--- a/auto/lib/perl/conf
+++ b/auto/lib/perl/conf
@@ -12,7 +12,7 @@
 if test -n "$NGX_PERL_VER"; then
     echo " + perl version: $NGX_PERL_VER"
 
-    if [ "`echo 'use 5.006001; print "OK"' | $NGX_PERL 2>&1`" != OK ]; then
+    if [ "`$NGX_PERL -e 'use 5.006001; print "OK"'`" != "OK" ]; then
         echo
         echo "$0: error: perl 5.6.1 or higher is required"
         echo
@@ -20,6 +20,14 @@
         exit 1;
     fi
 
+    if [ "`$NGX_PERL -MExtUtils::Embed -e 'print "OK"'`" != "OK" ]; then
+        echo
+        echo "$0: error: perl module ExtUtils::Embed is required"
+        echo
+
+        exit 1;
+    fi
+
     NGX_PERL_CFLAGS="$CFLAGS `$NGX_PERL -MExtUtils::Embed -e ccopts`"
     NGX_PM_CFLAGS=`$NGX_PERL -MExtUtils::Embed -e ccopts`