[Buildroot] [PATCH] crosstool-ng: add dependency to host-lzma if no lzma found

[Thomas De Schampheleire <patrickdepinguin+buildroot@gmail.com>]

Crosstool compilation fails when lzma is not present. If not present on the host
system, we should compile one ourselves.

This patch uses the already existing but seemingly unused check-host-lzma.sh
script in toolchain/dependencies.

Signed-off-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com>

---

I think the concept of first checking the host system, and only add a host-foo
dependency if needed is a common one. Therefore, I think we should consider
creating a function for it, something used like:

$(if $(call is-host-package-adequate,foo),,host-foo)

This function would return the path to the existing host package, if any, or
the empty string otherwise. The name for such a function is open for discussion
:-)

This mechanism could then be used to check for a recent-enough tar version
(recall from a previous patch series, old tar versions can cause problems when
unpacking archives containing hard-links, if the --strip-components option is
used).

Comments/suggestions are welcome...

diff --git a/package/crosstool-ng/crosstool-ng.mk b/package/crosstool-ng/crosstool-ng.mk
--- a/package/crosstool-ng/crosstool-ng.mk
+++ b/package/crosstool-ng/crosstool-ng.mk
@@ -4,6 +4,6 @@
 CROSSTOOL_NG_INSTALL_STAGING   = NO
 CROSSTOOL_NG_INSTALL_TARGET    = NO
 CROSSTOOL_NG_MAKE              = $(MAKE1)
-HOST_CROSSTOOL_NG_DEPENDENCIES = host-gawk host-automake $(if $(BR2_CCACHE),host-ccache)
+HOST_CROSSTOOL_NG_DEPENDENCIES = host-gawk host-automake $(if $(BR2_CCACHE),host-ccache) $(if $(shell toolchain/dependencies/check-host-lzma.sh),,host-lzma)
 
 $(eval $(call AUTOTARGETS,package,crosstool-ng,host))