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
-