Fix command spawning on Cygwin-based standalone image.

In the standalone image, we need a /bin/sh interpreter
for the sh and open-command functions to work. The / path
resolves to the installation directory, thanks to some
sysrooting logic in the Cygwin DLL. Thus, we just need
a sh.exe program in the bin directory, side by side
with txr.exe. This sh.exe program can translate the
"sh -c command" invocation to "cmd.exe /c command".

* Makefile (sh.exe): New target, built from cmdwrap.c.

* cmdwrap.c: New file.

* inst.nsi: Install sh.exe.

1 files changed, 1 insertions, 0 deletions

diff --git a/inst.nsi b/inst.nsi
index f89facd7..41a9691d 100644
--- a/inst.nsi
+++ b/inst.nsi
@@ -47,6 +47,7 @@ section "TXR"
   SetOutPath $INSTDIR\txr\bin
   File txr.exe
   File txr-win.exe
+  File sh.exe
   File c:\cygwin\bin\cygwin1.dll
   File c:\cygwin\bin\cyggcc_s-1.dll
   SetOutPath $INSTDIR\txr\doc