[Buildroot] [PATCH 1 of 3 v3] infra: support buildroot being located in /usr

[Thomas Petazzoni]

Dear Thomas De Schampheleire,

On Sat, 21 Jun 2014 17:01:47 +0200, Thomas De Schampheleire wrote:
> pkg-generic and pkg-autotools both perform sed replacements of /usr to
> $(STAGING_DIR)/usr, in .pc and .la files respectively. However, if buildroot
> itself is located in /usr, then STAGING_DIR also starts with /usr, and naive
> replacements of '/usr' can result in paths of the form:
>     /usr/buildroot/.../sysroot/usr/buildroot/.../sysroot/...
> 
> This patch makes the replacements more careful, by first replacing the known
> paths BASE_DIR and STAGING_DIR to tokens, then performing the actual
> replacement, and finally replacing the tokens with the corresponding paths.
> 
> Additionally it removes the unnecessary making of a backup copy in
> pkg-autotools.
> 
> Partially fixes bug #5750 (https://bugs.busybox.net/show_bug.cgi?id=5750)
> 
> Partially-based-on-a-patch-from: Ben Stoltz <benstoltz at gmail.com>
> Signed-off-by: Thomas De Schampheleire <thomas.de.schampheleire at gmail.com>

I've applied this patch, after adding the explanation comment proposed
by Arnout. However, I haven't implemented the other possible
improvements suggested by Arnout, which I believe can be proposed as
followup patches.

Thanks,

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com