configure: add flag to disable OpenSSL tests

OpenSSL messes up valgrind.

configure.ac

@@ -94,6 +94,11 @@ AC_ARG_ENABLE(tests,
     [use_tests=$enableval],
     [use_tests=yes])
 
+AC_ARG_ENABLE(openssl_tests,
+    AS_HELP_STRING([--enable-openssl-tests],[enable OpenSSL tests, if OpenSSL is available (default is auto)]),
+    [enable_openssl_tests=$enableval],
+    [enable_openssl_tests=auto])
+
 AC_ARG_ENABLE(experimental,
     AS_HELP_STRING([--enable-experimental],[allow experimental configure options (default is no)]),
     [use_experimental=$enableval],
@@ -323,6 +328,7 @@ esac
 if test x"$use_tests" = x"yes"; then
   SECP_OPENSSL_CHECK
   if test x"$has_openssl_ec" = x"yes"; then
+    if test x"$enable_openssl_tests" != x"no"; then
       AC_DEFINE(ENABLE_OPENSSL_TESTS, 1, [Define this symbol if OpenSSL EC functions are available])
       SECP_TEST_INCLUDES="$SSL_CFLAGS $CRYPTO_CFLAGS"
       SECP_TEST_LIBS="$CRYPTO_LIBS"
@@ -332,7 +338,15 @@ if test x"$use_tests" = x"yes"; then
         SECP_TEST_LIBS="$SECP_TEST_LIBS -lgdi32"
         ;;
       esac
-
+    fi
+  else
+    if test x"$enable_openssl_tests" = x"yes"; then
+      AC_MSG_ERROR([OpenSSL tests requested but OpenSSL with EC support is not available])
+    fi
+  fi
+else
+  if test x"$enable_openssl_tests" = x"yes"; then
+    AC_MSG_ERROR([OpenSSL tests requested but tests are not enabled])
   fi
 fi
 

src/tests.c

@@ -3500,12 +3500,14 @@ void run_ecdsa_end_to_end(void) {
 
 int test_ecdsa_der_parse(const unsigned char *sig, size_t siglen, int certainly_der, int certainly_not_der) {
     static const unsigned char zeroes[32] = {0};
+#ifdef ENABLE_OPENSSL_TESTS
     static const unsigned char max_scalar[32] = {
         0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff,
         0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xfe,
         0xba, 0xae, 0xdc, 0xe6, 0xaf, 0x48, 0xa0, 0x3b,
         0xbf, 0xd2, 0x5e, 0x8c, 0xd0, 0x36, 0x41, 0x40
     };
+#endif
 
     int ret = 0;