archive: fix stored paths when building under MSYS

[rokm]

When building CArchive package under MSYS, os.path.sep is Unix-style forward clash separator that is incompatible with bootloader (which on Windows expects back slash separators). Therefore, if we are on Windows and os.path.sep is forward slash, os.path.normpath() in CTOC.add() needs to be followed by explicit replacement of forward slashes with back slashes.

Otherwise, bootloader fails to extract nested files from archive in onefile builds that are created in MSYS environment.

Fixes second part of the issue reported in #5560.

[Legorooj]

Interesting... I was under the impression that windows supported / as a path seperator.

[rokm]

Interesting... I was under the impression that windows supported / as a path seperator.

Windows probably does, but our bootloader supports only \ as path separator on Windows:

pyinstaller/bootloader/src/pyi_global.h

Lines 139 to 157 in d772654

	#ifdef _WIN32
	#define PYI_PATHSEP ';'
	#define PYI_CURDIR '.'
	#define PYI_SEP '\\'
	/*
	* For some functions like strcat() we need to pass
	* string and not only char.
	*/
	#define PYI_SEPSTR "\\"
	#define PYI_PATHSEPSTR ";"
	#define PYI_CURDIRSTR "."
	#else
	#define PYI_PATHSEP ':'
	#define PYI_CURDIR '.'
	#define PYI_SEP '/'
	#define PYI_SEPSTR "/"
	#define PYI_PATHSEPSTR ":"
	#define PYI_CURDIRSTR "."
	#endif

For example, pyi_path_dirname on Windows essentially searches for last occurrence of PYI_SEP, so with gi/_gi-cpython-38.dll from #5560, it came up empty...

[Legorooj]

ah so it's a limitation of the bootloader, not the OS. of course.