Update JGit dependencies to fix building from source

A dependency on 'com.jcraft.jzlib' was added in JGit [1], so add that
to the dependencies for building JGit from source.

Also move the 'hamcrest-library' dependency out of WORKSPACE into the
jgit rules where it will be added conditionally.

Depends on [2] which harmonizes JGit's dependency names to align with
the names used in Gerrit since change I1e75690fe. Without [2], the
build will fail with errors like:

  "no such package '@commons_compress//jar'"

[1] https://git.eclipse.org/r/#/c/114907/
[2] https://git.eclipse.org/r/#/c/128348/

Change-Id: I33be13e7f36ec2bcacbb9eb0983c88c6f3082097

WORKSPACE

@@ -816,13 +816,6 @@ maven_jar(
     sha1 = "42a25dc3219429f0e5d060061f71acb49bf010a0",
 )
 
-# Only needed when jgit is built from the development tree
-maven_jar(
-    name = "hamcrest-library",
-    artifact = "org.hamcrest:hamcrest-library:1.3",
-    sha1 = "4785a3c21320980282f9f33d0d1264a69040538f",
-)
-
 TRUTH_VERS = "0.42"
 
 maven_jar(

lib/jgit/jgit.bzl

@@ -18,9 +18,23 @@ def jgit_repos():
             name = "jgit",
             path = LOCAL_JGIT_REPO,
         )
+        jgit_maven_repos_dev()
     else:
         jgit_maven_repos()
 
+def jgit_maven_repos_dev():
+    # Transitive dependencies from JGit's WORKSPACE.
+    maven_jar(
+        name = "hamcrest-library",
+        artifact = "org.hamcrest:hamcrest-library:1.3",
+        sha1 = "4785a3c21320980282f9f33d0d1264a69040538f",
+    )
+    maven_jar(
+        name = "jzlib",
+        artifact = "com.jcraft:jzlib:1.1.1",
+        sha1 = "a1551373315ffc2f96130a0e5704f74e151777ba",
+    )
+
 def jgit_maven_repos():
     maven_jar(
         name = "jgit-lib",