[CRIU] [PATCHv2] tools.mk: Define CC if not set to 'default'

[Zhang, Ning A]

Passes build with Android NDK/Clang in docker.

BR.
Ning.


在 2019-04-12五的 09:04 +0100，Radostin Stoyanov写道：
> 	FOO ?= bar
> 
> is equivalent to
> 
> 	ifeq ($(origin FOO), undefined)
> 	FOO = bar
> 	endif
> 
> However, when CC is not set its value is 'default' rather than
> 'undefined'.
> 
> From [1]:
> 
> 'undefined': if variable was never defined.
> 
> 'default': if variable has a default definition, as is usual with CC
> and so on. See Variables Used by Implicit Rules. Note that if you have
> redefined a default variable, the origin function will return the
> origin of the later definition.
> 
> [1] https://www.gnu.org/software/make/manual/make.html
> 
> Signed-off-by: Radostin Stoyanov <rstoyanov1 at gmail.com>
> ---
>  scripts/nmk/scripts/tools.mk | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/scripts/nmk/scripts/tools.mk b/scripts/nmk/scripts/tools.mk
> index d756358d5..8620ded7c 100644
> --- a/scripts/nmk/scripts/tools.mk
> +++ b/scripts/nmk/scripts/tools.mk
> @@ -4,9 +4,13 @@ ifndef ____nmk_defined__tools
>  # System tools shorthands
>  RM		:= rm -f
>  HOSTLD		?= ld
> -LD		?= $(CROSS_COMPILE)$(HOSTLD)
> +ifeq ($(origin LD), default)
> +LD		:= $(CROSS_COMPILE)$(HOSTLD)
> +endif
>  HOSTCC		?= gcc
> -CC		?= $(CROSS_COMPILE)$(HOSTCC)
> +ifeq ($(origin CC), default)
> +CC		:= $(CROSS_COMPILE)$(HOSTCC)
> +endif
>  CPP		:= $(CC) -E
>  AS		:= $(CROSS_COMPILE)as
>  AR		:= $(CROSS_COMPILE)ar