[source] tools/mpfr: Update to 3.1.5 and change to xz tarball

[LEDE Commits]

blogic pushed a commit to source.git, branch master:
https://git.lede-project.org/d88d55e0dbeb81b3781c31df5d53d27e2a4422ac

commit d88d55e0dbeb81b3781c31df5d53d27e2a4422ac
Author: diizzyy <diizzyy at users.noreply.github.com>
AuthorDate: Sun Oct 2 23:54:13 2016 +0200

    tools/mpfr: Update to 3.1.5 and change to xz tarball
    
    Updates mpfr to 3.1.5 and changes tarball format to xz
    
    Signed-off-by: Daniel Engberg daniel.engberg.lists at pyret.net
---
 tools/mpfr/Makefile | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/tools/mpfr/Makefile b/tools/mpfr/Makefile
index 3a2c339..47ff1c5 100644
--- a/tools/mpfr/Makefile
+++ b/tools/mpfr/Makefile
@@ -7,12 +7,12 @@
 include $(TOPDIR)/rules.mk
 
 PKG_NAME:=mpfr
-PKG_VERSION:=3.1.4
+PKG_VERSION:=3.1.5
 
 PKG_SOURCE_URL:=http://www.mpfr.org/mpfr-$(PKG_VERSION) \
 		@GNU/mpfr
-PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.bz2
-PKG_MD5SUM:=b8a2f6b0e68bef46e53da2ac439e1cf4
+PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.xz
+PKG_MD5SUM:=c4ac246cf9795a4491e7766002cd528f
 
 HOST_BUILD_PARALLEL:=1
 HOST_FIXUP:=autoreconf