fix: Don't assume program files folder locations

This checks where *program files* directories are located on a
Windows system, which are used for a fallback check after `git`
has not been found in a `PATH` search (to invoke `git` to find out
information such as the location of its system config file).

Previously, two hard-coded paths were used. These were correct for
the vast majority of 64-bit Windows systems, but were in practice
never correct on 32-bit Windows systems. Checking programmatically
for the locations should thus enable detection to succeed on more
systems and under more circumstances, and avoid other problems.

gix-path/src/env/git.rs

@@ -6,12 +6,8 @@ use once_cell::sync::Lazy;
 
 /// Other places to find Git in.
 #[cfg(windows)]
-pub(super) static ALTERNATIVE_LOCATIONS: Lazy<Vec<PathBuf>> = Lazy::new(|| {
-    vec![
-        "C:/Program Files/Git/mingw64/bin".into(),
-        "C:/Program Files (x86)/Git/mingw32/bin".into(),
-    ]
-});
+pub(super) static ALTERNATIVE_LOCATIONS: Lazy<Vec<PathBuf>> =
+    Lazy::new(|| locations_under_program_files(|key| std::env::var_os(key)));
 #[cfg(not(windows))]
 pub(super) static ALTERNATIVE_LOCATIONS: Lazy<Vec<PathBuf>> = Lazy::new(|| vec![]);