Upgrade JGit to 5.3.7.202002110540-r

JGit 5.3.7.202002110540-r adds
- new WindowCache metrics
- and enables using strong references to reference cache pages in the
WindowCache. Set core.packedGitUseStrongRefs = true to enable using
strong references to reference packfile pages cached in the WindowCache.
If this option is set Java gc can no longer flush the WindowCache to
free memory if the used heap comes close to the maximum heap size. On
the other hand this provides more predictable performance.

Documentation of core.packedGitUseStrongRefs is added in I895369a85,
which will reach stable-3.0 by merge later.

Change-Id: I8c080a16e25678dc6aeec9c21a6029965fb1ac5b

lib/jgit/jgit.bzl

@@ -1,6 +1,6 @@
 load("//tools/bzl:maven_jar.bzl", "MAVEN_CENTRAL", "maven_jar")
 
-_JGIT_VERS = "5.3.6.201910020505-r"
+_JGIT_VERS = "5.3.7.202002110540-r"
 
 _DOC_VERS = _JGIT_VERS  # Set to _JGIT_VERS unless using a snapshot
 
@@ -40,25 +40,25 @@ def jgit_maven_repos():
         name = "jgit-lib",
         artifact = "org.eclipse.jgit:org.eclipse.jgit:" + _JGIT_VERS,
         repository = _JGIT_REPO,
-        sha1 = "0b9085bd16c630412bfa50bcc509dcedfbbe16d3",
+        sha1 = "b1714d4917750d6fad0d19d3b0e258b373db819a",
     )
     maven_jar(
         name = "jgit-servlet",
         artifact = "org.eclipse.jgit:org.eclipse.jgit.http.server:" + _JGIT_VERS,
         repository = _JGIT_REPO,
-        sha1 = "d4e4d92f6faf44371f7cc3b53a6a97306ab3baaf",
+        sha1 = "cf61e6e00a758a6f33995e53883aede76d3b2400",
     )
     maven_jar(
         name = "jgit-archive",
         artifact = "org.eclipse.jgit:org.eclipse.jgit.archive:" + _JGIT_VERS,
         repository = _JGIT_REPO,
-        sha1 = "168492930b95ba743e9c29354b9ff5f9f3dfa777",
+        sha1 = "3c0b259040d3bc3a9e884a301055cf4f2e1bb1e2",
     )
     maven_jar(
         name = "jgit-junit",
         artifact = "org.eclipse.jgit:org.eclipse.jgit.junit:" + _JGIT_VERS,
         repository = _JGIT_REPO,
-        sha1 = "5574bb089515d729cf66290553bfbc47eb37c213",
+        sha1 = "f78409fb808c5a108c629ec3cba74cc6c14ebff2",
     )
 
 def jgit_dep(name):