rust: use rust-installer's way of disabling ldconfig

Instead of patching in a disable ldconfig argument, just use the way
exposed by the rust-installer scripts to disable running ldconfig.

Signed-off-by: Doug Goldstein <cardoe@cardoe.com>

recipes-devtools/rust/files/rust/0008-install-disable-ldconfig.patch

@@ -1,28 +0,0 @@
-From 2e6a496cb978e3bf885e4e2c3032a02b418c790d Mon Sep 17 00:00:00 2001
-From: Cody P Schafer <dev@codyps.com>
-Date: Tue, 26 May 2015 12:09:36 -0400
-Subject: [PATCH 8/9] install: disable ldconfig
-
----
- mk/install.mk | 5 +++--
- 1 file changed, 3 insertions(+), 2 deletions(-)
-
-diff --git a/mk/install.mk b/mk/install.mk
-index 430add7..6735dc7 100644
---- a/mk/install.mk
-+++ b/mk/install.mk
-@@ -13,8 +13,9 @@ RUN_INSTALLER = cd tmp/empty_dir && \
- 		--prefix="$(DESTDIR)$(CFG_PREFIX)" \
- 		--libdir="$(DESTDIR)$(CFG_LIBDIR)" \
- 		--mandir="$(DESTDIR)$(CFG_MANDIR)" \
--		"$(MAYBE_DISABLE_VERIFY)"
--		--disable-rewrite-paths
-+		"$(MAYBE_DISABLE_VERIFY)" \
-+		--disable-rewrite-paths \
-+		--disable-ldconfig
- 
- install:
- ifeq (root user, $(USER) $(patsubst %,user,$(SUDO_USER)))
--- 
-2.4.10
-

recipes-devtools/rust/rust-source.bb

@@ -19,7 +19,6 @@ SRC_URI_append = "\
         file://rust/0005-configure-support-bindir-and-extend-libdir-to-non-bl.patch \
         file://rust/0006-std-thread_local-workaround-for-NULL-__dso_handle.patch \
         file://rust/0007-mk-install-use-disable-rewrite-paths.patch \
-        file://rust/0008-install-disable-ldconfig.patch \
         file://rust/0009-Remove-crate-metadata-from-symbol-hashing.patch \
         file://rust/0010-rustc_trans-make-.note.rustc-look-more-like-debug-in.patch \
         file://rust/0011-Allow-overriding-crate_hash-with-C-crate_hash.patch \

recipes-devtools/rust/rust.inc

@@ -336,6 +336,9 @@ do_rust_arch_fixup[dirs] += "${WORKDIR}/mk-cfg"
 
 llvmdir = "${STAGING_DIR_NATIVE}/${prefix_native}"
 
+# prevent the rust-installer scripts from calling ldconfig
+export CFG_DISABLE_LDCONFIG="notempty"
+
 do_configure () {
     # Note: when we adjust the generated targets, rust doesn't rebuild (even
     # when it should), so for now we need to remove the build dir to keep