[PATCH 1/2 v2] msvcrt: Optimize _strupr implementation in C locale

[Piotr Caban]

Don't write to input buffer when there's nothing to change (for bug
39979).

Signed-off-by: Piotr Caban 
---
v2:
  - fixed win_skip message

dlls/msvcrt/string.c | 24 +++++++++++++++++++++---
  1 file changed, 21 insertions(+), 3 deletions(-)