vfs and newlib: small fixes

- spaces->tabs in tasks.c
- update vfs_uart.c to use per-UART locks
- add license to vfs_uart.c
- allocate separate streams for stdout, stdin, stderr, so that they can be independently reassigned
- fix build system test failure

components/newlib/component.mk

@@ -1,8 +1,5 @@
-COMPONENT_ADD_LDFLAGS := $(abspath lib/libc.a) $(abspath lib/libm.a)
+COMPONENT_ADD_LDFLAGS := $(abspath lib/libc.a) $(abspath lib/libm.a) -lnewlib
 
-
-define COMPONENT_BUILDRECIPE
-	#Nothing to do; this does not generate a library.
-endef
+COMPONENT_ADD_INCLUDEDIRS := include platform_include
 
 include $(IDF_PATH)/make/component_common.mk