autotools: Disable eager MSan in ctime_tests

Co-authored-by: Hennadii Stepanov <32963518+hebasto@users.noreply.github.com>

build-aux/m4/bitcoin_secp.m4

@@ -45,6 +45,18 @@ fi
 AC_MSG_RESULT($has_valgrind)
 ])
 
+AC_DEFUN([SECP_MSAN_CHECK], [
+AC_MSG_CHECKING(whether MemorySanitizer is enabled)
+AC_COMPILE_IFELSE([AC_LANG_SOURCE([[
+  #if defined(__has_feature)
+  #  if __has_feature(memory_sanitizer)
+  #    error "MemorySanitizer is enabled."
+  #  endif
+  #endif
+  ]])], [msan_enabled=no], [msan_enabled=yes])
+AC_MSG_RESULT([$msan_enabled])
+])
+
 dnl SECP_TRY_APPEND_CFLAGS(flags, VAR)
 dnl Append flags to VAR if CC accepts them.
 AC_DEFUN([SECP_TRY_APPEND_CFLAGS], [