use #pragma comment(lib) with _MSC_VER only

Avoid this warning when compiled with llvm/gcc + mingw-w64 and
`USE_BCRYPTGENRANDOM` enabled:

```
../providers/implementations/rands/seeding/rand_win.c:31:11: warning: unknown pragma ignored [-Wunknown-pragmas]
          ^
1 warning generated.
```

CLA: trivial

Reviewed-by: Hugo Landau <hlandau@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from #18709)

(cherry picked from commit 695cb63)

providers/implementations/rands/seeding/rand_win.c

@@ -28,7 +28,9 @@
 
 # ifdef USE_BCRYPTGENRANDOM
 #  include <bcrypt.h>
-#  pragma comment(lib, "bcrypt.lib")
+#  ifdef _MSC_VER
+#   pragma comment(lib, "bcrypt.lib")
+#  endif
 #  ifndef STATUS_SUCCESS
 #   define STATUS_SUCCESS ((NTSTATUS)0x00000000L)
 #  endif