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, 11 insertions, 0 deletions

diff --git a/scripts/basic/split-include.c b/scripts/basic/split-include.c
index 290bea2fb..a85ede8ef 100644
--- a/scripts/basic/split-include.c
+++ b/scripts/basic/split-include.c
@@ -197,13 +197,21 @@ int main(int argc, const char * argv [])
      * So by having an initial \n, strstr will find exact matches.
      */
 
+#ifdef __MINGW32__
+    fp_find = popen("find . -type f -name \"*.h\" -print", "r");
+#else
     fp_find = popen("find * -type f -name \"*.h\" -print", "r");
+#endif
     if (fp_find == 0)
         ERROR_EXIT( "find" );
 
     line[0] = '\n';
     while (fgets(line+1, buffer_size, fp_find))
     {
+#ifdef __MINGW32__
+        line[2] = '\n';
+# define line (line + 2)
+#endif
         if (strstr(list_target, line) == NULL)
         {
             /*
@@ -226,6 +234,9 @@ int main(int argc, const char * argv [])
                     ERROR_EXIT(line);
             }
         }
+#ifdef __MINGW32__
+# undef line
+#endif
     }
 
     if (pclose(fp_find) != 0)