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, 5 insertions, 5 deletions

diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
index 5b4db5c2c..b61ff8b42 100644
--- a/scripts/Kbuild.include
+++ b/scripts/Kbuild.include
@@ -52,25 +52,25 @@ endef
 # as-option
 # Usage: cflags-y += $(call as-option, -Wa$(comma)-isa=foo,)
 
-as-option = $(shell if $(CC) $(CFLAGS) $(1) -Wa,-Z -c -o /dev/null \
-             -xassembler /dev/null > /dev/null 2>&1; then echo "$(1)"; \
+as-option = $(shell if $(CC) $(CFLAGS) $(1) -Wa,-Z -c -o - \
+             -xassembler - </dev/null > /dev/null 2>&1; then echo "$(1)"; \
              else echo "$(2)"; fi ;)
 
 # cc-option
 # Usage: cflags-y += $(call cc-option, -march=winchip-c6, -march=i586)
 
-cc-option = $(shell if $(CC) $(CFLAGS) $(1) -S -o /dev/null -xc /dev/null \
+cc-option = $(shell if $(CC) $(CFLAGS) $(1) -S -o - -xc - </dev/null \
              > /dev/null 2>&1; then echo "$(1)"; else echo "$(2)"; fi ;)
 
 # hostcc-option
 # Usage: hostcflags-y += $(call hostcc-option, -march=winchip-c6, -march=i586)
 
-hostcc-option = $(shell if $(HOSTCC) $(HOSTCFLAGS) $(1) -S -o /dev/null -xc /dev/null \
+hostcc-option = $(shell if $(HOSTCC) $(HOSTCFLAGS) $(1) -S -o - -xc - </dev/null \
              > /dev/null 2>&1; then echo "$(1)"; else echo "$(2)"; fi ;)
 
 # cc-option-yn
 # Usage: flag := $(call cc-option-yn, -march=winchip-c6)
-cc-option-yn = $(shell if $(CC) $(CFLAGS) $(1) -S -o /dev/null -xc /dev/null \
+cc-option-yn = $(shell if $(CC) $(CFLAGS) $(1) -S -o - -xc - </dev/null \
                 > /dev/null 2>&1; then echo "y"; else echo "n"; fi;)
 
 # cc-option-align