Ignore the coding style change commit during git blame

git supports ignoring specific revs during git blame, configured via

  $ git config blame.ignoreRevsFile .git-blame-ignore-revs

Let's make this easier for developers to set up, starting with the
one massive coding style change commit.

Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1748>

.git-blame-ignore-revs

@@ -0,0 +1,24 @@
+# This file contains revisions to be ignored by git blame.
+# These revisions are expected to be formatting-only changes.
+#
+# Calling `git blame --ignore-revs-file .git-blame-ignore-revs` will
+# tell git blame to ignore changes made by these revisions when assigning
+# assigning blame, as if the change never happened.
+#
+# You can enable this as a default for your local repository by running
+# `git config blame.ignoreRevsFile .git-blame-ignore-revs`
+# Important: if you do this, then switch to a branch without this file,
+# `git blame` will fail with an error.
+#
+
+# Introduce a consistent coding style
+9838b7032ea9792bec21af424c53c07078636d21
+
+# Drop trailing whitespaces
+732fd7e571b81d63aa44d6e4cf55883479e88f2f
+
+# glamor: Apply x-indent.sh.
+d84d71029ae9e462559d64eff7259e2cc7732fac
+
+# indent fixes (OMG SO UGLY), and nuke old RCS keywords.
+6d7083bd69724586338d79784655328f1fcd2ae5