[compiler-rt] [llvm] [sanitizer_common] Add experimental flag to tweak dlopen(<main program>) (PR #71715)

[Thurston Dang via llvm-commits]

================
@@ -6307,7 +6308,36 @@ INTERCEPTOR(int, fclose, __sanitizer_FILE *fp) {
 INTERCEPTOR(void*, dlopen, const char *filename, int flag) {
   void *ctx;
   COMMON_INTERCEPTOR_ENTER_NOIGNORE(ctx, dlopen, filename, flag);
-  if (filename) COMMON_INTERCEPTOR_READ_STRING(ctx, filename, 0);
+
+  if (filename) {
+    COMMON_INTERCEPTOR_READ_STRING(ctx, filename, 0);
+
+#  if !SANITIZER_DYNAMIC
----------------
thurstond wrote:

```
error: use of undeclared identifier 'SANITIZER_DYNAMIC'
    if constexpr (!SANITIZER_DYNAMIC) {
                   ^
1 error generated.
```

(It's usually not defined at all.)

https://github.com/llvm/llvm-project/pull/71715