Build blame cache as own java_library

This is a first step towards properly packaging of blame cache in Gerrit
server which is needed for [1]. [1] currently (PS-44) depends on the
whole gitiles-servlet and this leads to a:

  java.lang.NoClassDefFoundError: com/google/template/soy/SoyFileSet

caused by packaging the gitiles-servlet in the Gerrit core but without
all of its dependencies.

[1] https://gerrit-review.googlesource.com/72798

Change-Id: I9326b30962c21082b3d152eb6397ddcf767d1ce3

gitiles-servlet/BUCK

diff --git a/gitiles-servlet/BUCK b/gitiles-servlet/BUCK
index 8a0de1f..81c06e2 100644
--- a/gitiles-servlet/BUCK
+++ b/gitiles-servlet/BUCK
@@ -1,6 +1,7 @@
 SRCS = glob(['src/main/java/**/*.java'])
 RSRC = glob(['src/main/resources/**/*'])
 DEPS = [
+  '//blame-cache:lib',
   '//lib:commons-lang',
   '//lib:grappa',
   '//lib:gson',