Add longPathAware manifest to enable long paths on Windows

[cristianadam]

Fixes: #1900 when the registry key Computer\HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\FileSystem\LongPathsEnabled (Type: REG_DWORD) is set to 1

See https://learn.microsoft.com/en-us/windows/win32/fileio/maximum-file-path-limitation for more details.

[cristianadam]

Given the following path: "c:\Projects\C++\this is a rather long path for a path on windows where long paths are a problem with the limit of two hundred fifty characters but there is a solution which implies adding a registry key and configuring the project to include a manifest\build.ninja" with build.ninja containing the string meh:

Ninja went from this error message:

c:\Projects\C++\this is a rather long path for a path on windows where long paths are a problem with the limit of two hundred fifty characters but there is a solution which implies adding a registry key and configuring the project to include a manifest
$ ninja
ninja: error: loading 'build.ninja': The system cannot find the path specified.

to this error message:

c:\Projects\C++\this is a rather long path for a path on windows where long paths are a problem with the limit of two hundred fifty characters but there is a solution which implies adding a registry key and configuring the project to include a manifest
$ ninja
ninja: error: build.ninja:1: expected '=', got newline
meh
   ^ near here

[jhasse]

wait a minute ... wasn't this supposed to only work with the unicode WinAPI functions ending with W? We're using the *A functions. I remember testing this a few years ago and it didn't have any effect. Has something changed?

[cristianadam]

wait a minute ... wasn't this supposed to only work with the unicode WinAPI functions ending with W? We're using the *A functions. I remember testing this a few years ago and it didn't have any effect. Has something changed?

Above you have my test case. With the manifest entry and the registry key ninja was able to read the build.ninja file. Without it failed to find the file.

The same thing works also for MinGW GCC https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107974
Visual C++ doesn't like it, as seen at https://developercommunity.visualstudio.com/t/compiler-cant-find-source-file-in-path/10221576

Ninja is the missing part from having a working setup with GCC or Clang on Windows.