Makefile.include: remove repeated OS declaration

Makefile.include

@@ -105,7 +105,7 @@ include $(RIOTMAKE)/utils/strings.mk
 
 
 # UNAME is always needed so use simple variable expansion so only evaluated once
-UNAME := $(OS -m)
+UNAME := $(shell uname -m -s)
 OS = $(word 1, $(UNAME))
 OS_ARCH = $(word 2, $(UNAME))
 

boards/native/Makefile.dep

@@ -6,7 +6,6 @@ ifneq (,$(filter mtd,$(USEMODULE)))
   USEMODULE += mtd_native
 endif
 
-OS := $(shell uname -s)
 ifneq (,$(filter can,$(USEMODULE)))
   ifeq ($(OS),Linux)
     USEMODULE += can_linux

boards/native/Makefile.include

@@ -5,8 +5,6 @@ export NATIVEINCLUDES += -I$(RIOTBASE)/drivers/include/
 
 USEMODULE += native-drivers
 
-OS := $(shell uname -s)
-
 ifeq ($(OS),Darwin)
   DEBUGGER ?= lldb
 else
@@ -29,21 +27,17 @@ ifeq (,$(filter -std=%, $(CFLAGS)))
   CFLAGS += -std=gnu99
 endif
 
-OS_ARCH := $(shell uname -m)
 ifeq ($(OS_ARCH),x86_64)
   CFLAGS += -m32
 endif
 ifneq (,$(filter -DDEVELHELP,$(CFLAGS)))
   CFLAGS += -fstack-protector-all
 endif
-OS := $(shell uname -s)
 ifeq ($(OS),FreeBSD)
-  OS_ARCH := $(shell uname -m)
   ifeq ($(OS_ARCH),amd64)
     CFLAGS += -m32 -DCOMPAT_32BIT -B/usr/lib32
   endif
 endif
-OS := $(shell uname -s)
 ifeq ($(OS),Darwin)
   CFLAGS += -Wno-deprecated-declarations
 endif
@@ -52,13 +46,10 @@ endif
 CXXUWFLAGS +=
 CXXEXFLAGS +=
 
-OS_ARCH := $(shell uname -m)
 ifeq ($(OS_ARCH),x86_64)
   export LINKFLAGS += -m32
 endif
-OS := $(shell uname -s)
 ifeq ($(OS),FreeBSD)
-  OS_ARCH := $(shell uname -m)
   ifeq ($(OS_ARCH),amd64)
     export LINKFLAGS += -m32 -DCOMPAT_32BIT -L/usr/lib32 -B/usr/lib32
   endif
@@ -69,7 +60,6 @@ endif
 
 # clean up unused functions
 CFLAGS += -ffunction-sections -fdata-sections
-OS := $(shell uname -m)
 ifeq ($(OS),Darwin)
   export LINKFLAGS += -Wl,-dead_strip
 else
@@ -123,7 +113,6 @@ endif
 
 # backward compatability with glibc <= 2.17 for native
 ifeq ($(CPU),native)
-  OS := $(shell uname -s)
   ifeq ($(OS),Linux)
     ifeq ($(shell ldd --version |  awk '/^ldd/{if ($$NF < 2.17) {print "yes"} else {print "no"} }'),yes)
 	  LINKFLAGS += -lrt
@@ -134,7 +123,6 @@ endif
 # clumsy way to enable building native on osx:
 BUILDOSXNATIVE = 0
 ifeq ($(CPU),native)
- OS := $(shell uname -s)
   ifeq ($(OS),Darwin)
     BUILDOSXNATIVE = 1
   endif

cpu/native/Makefile

@@ -3,7 +3,6 @@ MODULE = cpu
 DIRS += periph
 DIRS += vfs
 
-OS := $(shell uname -s)
 ifeq ($(OS),Darwin)
   CFLAGS += -D_XOPEN_SOURCE=600 -D_DARWIN_C_SOURCE
 endif

pkg/fatfs/Makefile.include

@@ -16,7 +16,6 @@ else
   CFLAGS += -DFATFS_FFCONF_OPT_FS_NORTC=1
 endif
 
-OS := $(shell uname -s)
 ifeq ($(OS),Darwin)
   CFLAGS += -Wno-empty-body
 endif