Detect ECDSA by checking header existence.

--- configure.in.orig	2013-04-23 07:13:02.191893497 +0200
+++ configure.in	2013-04-23 07:27:48.630090319 +0200
@@ -766,36 +766,13 @@ esac
 		AC_CHECK_FUNCS(EVP_sha256 EVP_sha384 EVP_sha512)
 
 		AC_MSG_CHECKING(for OpenSSL ECDSA support)
-		have_ecdsa=""
-		AC_TRY_RUN([
-#include <stdio.h>
-#include <openssl/ecdsa.h>
-#include <openssl/objects.h>
-int main() {
-	EC_KEY *ec256, *ec384;
-
-#if !defined(HAVE_EVP_SHA256) || !defined(HAVE_EVP_SHA384)
-	return (1);
-#endif
-	ec256 = EC_KEY_new_by_curve_name(NID_X9_62_prime256v1);
-	ec384 = EC_KEY_new_by_curve_name(NID_secp384r1);
-	if (ec256 == NULL || ec384 == NULL)
-		return (2);
-	return (0);
-}
-],
-		[AC_MSG_RESULT(yes)
-		have_ecdsa="yes"],
-		[AC_MSG_RESULT(no)
-		have_ecdsa="no"])
-		case $have_ecdsa in
-		yes)
-			OPENSSL_ECDSA="yes"
+		if test -f $use_openssl/include/openssl/ecdsa.h
+		then
 			AC_DEFINE(HAVE_OPENSSL_ECDSA)
-			;;
-		*)
-			;;
-		esac
+			AC_MSG_RESULT(yes)
+		else
+			AC_MSG_RESULT(no)
+		fi
 
 		AC_MSG_CHECKING(for OpenSSL GOST support)
 		have_gost=""