Updated tarball, add spkg-src and fix instructions

Author: jdemeyer

build/pkgs/mpir/SPKG.txt

@@ -25,6 +25,6 @@ See http://www.mpir.org
    - We currently don't use anything of GMP's/MPIR's CC setting, and matching
      with the current compiler (`$CC`) is perhaps suboptimal.
  * Remove some files / directories not needed for Sage from upstream:
-     rm -rf src/build.vc*             # Microsoft Visual C build files
-     rm -rf src/yasm/Mkfiles/{dj,vc*} # DJGPP, Microsoft Visual C
-   (Saves 13 of 40 MB uncompressed.)
+     - build.vc* directories (Microsoft Visual C build files)
+ * 3.0.0-644faf502c56f97d9accd301965fc57d6ec70868
+   was created by running the spkg-src script.

build/pkgs/mpir/checksums.ini

@@ -1,4 +1,4 @@
 tarball=mpir-VERSION.tar.bz2
-sha1=1f7081c2f4a83fb4e9e3453bbafb6aa18f1c5d5a
-md5=308f4a981c0a2e796aa41ff3ac805b81
-cksum=2473237225
+sha1=30044be9f48ce15ddfc8871bde14e363fe2f46ea
+md5=55e9e31d6371b30dd046f16333c84499
+cksum=1799000157

build/pkgs/mpir/package-version.txt

@@ -1 +1 @@
-3.0.1.p0
+3.0.0-644faf502c56f97d9accd301965fc57d6ec70868

build/pkgs/mpir/spkg-src

@@ -0,0 +1,43 @@
+#!/usr/bin/env bash
+
+set -e
+
+if [ -z "$SAGE_DISTFILES" ]; then
+    echo >&2 "SAGE_DISTFILES undefined ... exiting"
+    echo >&2 "Maybe run 'sage --sh'?"
+    exit 1
+fi
+
+set -e
+
+PACKAGEVERSION=`cat $SAGE_ROOT/build/pkgs/mpir/package-version.txt`
+MPIRVERSION=mpir-`echo $PACKAGEVERSION | sed 's/-.*//'`
+TARBALLVERSION="mpir-$PACKAGEVERSION"
+
+# Get the sources
+cd "$SAGE_DISTFILES"
+rm -rf mpir
+git clone https://github.com/wbhart/mpir.git mpir
+cd mpir
+git checkout 644faf502c56f97d9accd301965fc57d6ec70868
+
+# Add auto-generated files
+./autogen.sh
+
+# Create the tarball
+./configure
+make dist-bzip2
+
+# Unpack the tarball, remove some unwanted stuff
+tar xjf $MPIRVERSION.tar.bz2
+find $MPIRVERSION -name 'build.vc*' -prune -exec rm -r {} \;
+
+# Repackage the tarball and put it in SAGE_DISTFILES
+mv $MPIRVERSION $TARBALLVERSION
+tar c $TARBALLVERSION | bzip2 --best >../$TARBALLVERSION.tar.bz2
+sage-package fix-checksum mpir
+
+# Cleanup
+cd "$SAGE_DISTFILES"
+rm -rf mpir
+echo "New MPIR tarball is ready in $SAGE_DISTFILES/$TARBALLVERSION.tar.bz2"