build system: allow building with w64devkit

Make some adjustments to the build system to allow busybox-w32
to be built with w64devkit:

- Strip drive prefix from CURDIR in Makefile to avoid confusing
  make with colons.

- Limit file redirection to a subshell in the usage_compressed and
  embedded_scripts scripts.  Otherwise it isn't possible to move
  the open generated file on Windows.

- Change the option tests in Kbuild.include to allow for /dev/null
  not existing on Windows.

- Create host binaries without a '.exe' extension.  Otherwise they're
  rebuilt more often than necessary.

- Modify split-include.c to allow for Windows' popen() not expanding
  wildcards.

(GitHub issue #239)

1 files changed, 2 insertions, 0 deletions

diff --git a/scripts/embedded_scripts b/scripts/embedded_scripts
index 205ac591a..8407c1f78 100755
--- a/scripts/embedded_scripts
+++ b/scripts/embedded_scripts
@@ -90,6 +90,7 @@ concatenate_scripts() {
         done
 }
 
+(
 exec >"$target.$$"
 
 if [ $n -ne 0 ]
@@ -127,5 +128,6 @@ then
                 -e 's/$/ \\/'
         printf '\n'
 fi
+)
 
 mv -- "$target.$$" "$target"