Merge topic 'custom-command-output-hash-character'

8d2a503c1e add_custom_command: Allow OUTPUT filenames containing a hash '#' character
b38000d774 cmGlobalXCodeGenerator: Re-implement legacy makefile path escaping
d929089687 cmGlobalXCodeGenerator: Do not use legacy makefile escaping in shell commands
d61fc2c52e cmGlobalXCodeGenerator: Migrate legacy makefile path escaping to local helper
6010e007c7 cmState: Add method to check for the Borland Makefiles generator

Acked-by: Kitware Robot <kwrobot@kitware.com>
Merge-request: !9514