PX4: enable ccache on windows build

mk/find_tools.mk

@@ -22,7 +22,8 @@ ifeq ($(findstring CYGWIN, $(SYSTYPE)),CYGWIN)
   FIND_TOOL    =  $(firstword $(wildcard $(addsuffix /$(1).exe,$(TOOLPATH))))
 endif
 ifeq ($(findstring MINGW, $(SYSTYPE)),MINGW)
-  TOOLPATH :=  $(ARDUINO)/hardware/tools/avr/bin
+  # expect that tools are on the path
+  TOOLPATH :=  $(subst :, ,$(PATH))
   FIND_TOOL    =  $(firstword $(wildcard $(addsuffix /$(1).exe,$(TOOLPATH))))
 endif
 
@@ -84,6 +85,7 @@ ZYNQ_OBJCOPY :=  arm-xilinx-linux-gnueabi-objcopy
 
 # enable ccache if installed
 CCACHE :=  $(call FIND_TOOL,ccache)
+export CCACHE
 
 CXX = $(CCACHE) $($(TOOLCHAIN)_CXX)
 CC = $(CCACHE) $($(TOOLCHAIN)_CC)

mk/px4_targets.mk

@@ -50,8 +50,8 @@ WARNFLAGS = -Wno-psabi -Wno-packed -Wno-error=double-promotion -Wno-error=unused
 # avoid PX4 submodules
 export GIT_SUBMODULES_ARE_EVIL = 1
 
-PX4_MAKE = $(v) GIT_SUBMODULES_ARE_EVIL=1 make -C $(SKETCHBOOK) -f $(PX4_ROOT)/Makefile EXTRADEFINES="$(SKETCHFLAGS) $(WARNFLAGS) "'$(EXTRAFLAGS)' APM_MODULE_DIR=$(SKETCHBOOK) SKETCHBOOK=$(SKETCHBOOK) PX4_ROOT=$(PX4_ROOT) NUTTX_SRC=$(NUTTX_SRC) MAXOPTIMIZATION="-Os" UAVCAN_DIR=$(UAVCAN_DIR)
-PX4_MAKE_ARCHIVES = make -C $(PX4_ROOT) NUTTX_SRC=$(NUTTX_SRC) archives MAXOPTIMIZATION="-Os" 
+PX4_MAKE = $(v) GIT_SUBMODULES_ARE_EVIL=1 make -C $(SKETCHBOOK) -f $(PX4_ROOT)/Makefile EXTRADEFINES="$(SKETCHFLAGS) $(WARNFLAGS) "'$(EXTRAFLAGS)' APM_MODULE_DIR=$(SKETCHBOOK) SKETCHBOOK=$(SKETCHBOOK) CCACHE=$(CCACHE) PX4_ROOT=$(PX4_ROOT) NUTTX_SRC=$(NUTTX_SRC) MAXOPTIMIZATION="-Os" UAVCAN_DIR=$(UAVCAN_DIR)
+PX4_MAKE_ARCHIVES = make -C $(PX4_ROOT) NUTTX_SRC=$(NUTTX_SRC) CCACHE=$(CCACHE) archives MAXOPTIMIZATION="-Os" 
 
 .PHONY: module_mk
 module_mk: