linux: improve support for cross-compiling

linux: improve support for cross-compiling

This CL adds support for a 'sysroot' GYP define, that should point to the target root filesystem for cross-compilation.
It passes that argument to the compiler and linker which uses it to prefix its hard-coded path (e.g. /usr/include)
It also points pkg-config to look for package configs there, and rewrite the paths to be prefixed by 'sysroot' (since pkg-config doesn't do it itself)

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=25418

[sgk, 2009-09-03 23:49:35]

http://codereview.chromium.org/199016/diff/1/2
File build/common.gypi (left):

http://codereview.chromium.org/199016/diff/1/2#oldcode769
Line 769: }
white space at end-of-line?

http://codereview.chromium.org/199016/diff/1/3
File build/linux/pkg-config-wrapper (right):

http://codereview.chromium.org/199016/diff/1/3#newcode3
Line 3: rewrite=`dirname $0`/rewrite_dirs.py
Move below the usage check; no sense calling dirname if we won't do anything.

http://codereview.chromium.org/199016/diff/1/3#newcode8
Line 8: echo "usage: $0 /path/to/sysroot [pkg-config-arguments]"
Redirect to stderr:

echo "usage: $0 /path/to/sysroot [pkg-config-arguments]" >&2

http://codereview.chromium.org/199016/diff/1/4
File build/linux/rewrite_dirs.py (right):

http://codereview.chromium.org/199016/diff/1/4#newcode53
Line 53: sysroot = ''
???  The pkg_config_wrapper script treats lack of a sysroot argument as an
error.  Is there a reason to not make them consistent?

http://codereview.chromium.org/199016/diff/1/5
File build/linux/system.gyp (right):

http://codereview.chromium.org/199016/diff/1/5#newcode24
Line 24: '<!@(<(pkg-config) --cflags gtk+-2.0 gthread-2.0)',
This ends up looking really clean.  Nice.

[piman, 2009-09-04 00:09:10]

http://codereview.chromium.org/199016/diff/1/2
File build/common.gypi (left):

http://codereview.chromium.org/199016/diff/1/2#oldcode769
Line 769: }
On 2009/09/03 23:49:35, sgk wrote:
> white space at end-of-line?

It adds the missing LF at the end of the file. It got added automatically by
vim, I can remove it if you want, but this is consistent with other files.

http://codereview.chromium.org/199016/diff/1/3
File build/linux/pkg-config-wrapper (right):

http://codereview.chromium.org/199016/diff/1/3#newcode3
Line 3: rewrite=`dirname $0`/rewrite_dirs.py
On 2009/09/03 23:49:35, sgk wrote:
> Move below the usage check; no sense calling dirname if we won't do anything.

Done.

http://codereview.chromium.org/199016/diff/1/3#newcode8
Line 8: echo "usage: $0 /path/to/sysroot [pkg-config-arguments]"
On 2009/09/03 23:49:35, sgk wrote:
> Redirect to stderr:
> 
> echo "usage: $0 /path/to/sysroot [pkg-config-arguments]" >&2
> 

Done.

http://codereview.chromium.org/199016/diff/1/4
File build/linux/rewrite_dirs.py (right):

http://codereview.chromium.org/199016/diff/1/4#newcode53
Line 53: sysroot = ''
On 2009/09/03 23:49:35, sgk wrote:
> ???  The pkg_config_wrapper script treats lack of a sysroot argument as an
> error.  Is there a reason to not make them consistent?

No good reason. Fixed.

[sgk, 2009-09-04 00:16:50]

lgtm

http://codereview.chromium.org/199016/diff/1/2
File build/common.gypi (left):

http://codereview.chromium.org/199016/diff/1/2#oldcode769
Line 769: }
On 2009/09/04 00:09:10, piman wrote:
> On 2009/09/03 23:49:35, sgk wrote:
> > white space at end-of-line?
> 
> It adds the missing LF at the end of the file. It got added automatically by
> vim, I can remove it if you want, but this is consistent with other files.
> 

No, consistency is good.  Just wanted to make sure it wasn't an oversight.