We don't currently autoreconf pkg-config for the target as we don't need
--with-sysroot support, which means PKG_CONFIG_SYSROOT=NULL wasn't
passed, breaking the build.
Fix it by reworking the patch to only pass this if --with-sysroot is given,
and handle the not set case in main.c.
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
Similar to the --with-pc-path option. It works just like the existing
PKG_CONFIG_SYSROOT_DIR environment variable, but compiled in.
The environment variable overrides this default setting if set.
This way we don't need to pass PKG_CONFIG_SYSROOT_DIR in the environment
when building for the target, and it is easier to reuse pkg-config outside
BR (E.G. for the SDK) without having to setup special environment
variables.
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
