Added the scripts git-svnup/git-svnrevert to utils/git-svn.

It makes more sense to have git-svnup here than catting said file in the
documentation (where we should rather point users to this directory).
I included git-svnrevert as an additional gift to the community. I will update
the documentation in a second commit later today.

git-svnrevert takes in a git hash for a commit, looks up the svn revision for
said commit and then creates the normal git revert commit message with the one
liner message, except instead of saying

  Revert "<<<INSERT ONELINER HERE>>>"

  This reverts commit <<<INSERT GITHASH HERE>>>

It says:

  Revert "<<<INSERT ONELINER HERE>>>"

  This reverts commit r<<<INSERT SVN REVISION HERE>>>

so git hashes will not escape into our svn logs (which just look unseemly).

llvm-svn: 180587

1 files changed, 15 insertions, 0 deletions

diff --git a/llvm/utils/git-svn/git-svnup b/llvm/utils/git-svn/git-svnup
new file mode 100755
index 00000000000..3321f6ba08a
--- /dev/null
+++ b/llvm/utils/git-svn/git-svnup
@@ -0,0 +1,15 @@
+#!/bin/bash
+
+if [ -n "`git status -uno -s --porcelain`" ]; then
+    echo "You have unstashed changes. Can not update repository..."
+    git status -uno
+    exit 1
+fi
+
+git fetch
+OLD_BRANCH=$(git rev-parse --abbrev-ref HEAD)
+git checkout master 2> /dev/null
+git svn rebase -l
+git checkout $OLD_BRANCH 2> /dev/null
+
+exit 0