Re: [PATCH 2/2] build: don't duplicate substitution of make variables

> Thanks to our 'GIT_CONF_SUBST' layer in configure.ac, a make variable 'VAR'
> can be defined to a value 'VAL' at ./configure runtime in our build system
> simply by using "GIT_CONF_SUBST([VAR], [VAL])" in configure.ac, rather than
> having both to call "AC_SUBST([VAR], [VAL])" in configure.ac and adding the
> 'VAR = @VAR@' definition in config.mak.in.  Less duplication, less margin
> for error, less possibility of confusion.
>
> While at it, fix some formatting issues in configure.ac that unnecessarily
> obscured the code flow.
>
> Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>
> ---
>  config.mak.in |  49 --------------------
>  configure.ac  | 144 +++++++++++++++++++++++++++++++---------------------------
>  2 files changed, 76 insertions(+), 117 deletions(-)

> diff --git a/configure.ac b/configure.ac
> index 450bbe7..da1f41f 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -267,6 +267,8 @@ AS_HELP_STRING([],           [ARG can be also prefix for libpcre library and hea
>  	USE_LIBPCRE=YesPlease
>  	LIBPCREDIR=$withval
>  	AC_MSG_NOTICE([Setting LIBPCREDIR to $LIBPCREDIR])
> +        dnl USE_LIBPCRE can still be modified below, so don't substitute
> +        dnl it yet.
>  	GIT_CONF_SUBST([LIBPCREDIR])
>      fi)
>  #
> ...
>  AC_CHECK_FUNC([hstrerror],
> -	[],
> +    [],