win32: use a static buffer in get_system_drive()

Allocate static storage for the system drive string instead of
making a new allocation on every call.  This is easier to manage.

Adds 16 bytes.

1 files changed, 1 insertions, 1 deletions

diff --git a/include/mingw.h b/include/mingw.h
index 5c0b0a7f4..91e4dc1a5 100644
--- a/include/mingw.h
+++ b/include/mingw.h
@@ -546,7 +546,7 @@ void hide_console(void);
 
 int unc_root_len(const char *dir);
 int root_len(const char *path);
-char *get_system_drive(void);
+const char *get_system_drive(void);
 int chdir_system_drive(void);
 char *xabsolute_path(char *path);
 char *get_drive_cwd(const char *path, char *buffer, int size);