icu4c: add bottle regex.

Library/Homebrew/bottle_version.rb

@@ -8,7 +8,8 @@ class BottleVersion < Version
     return m.captures.first unless m.nil?
 
     # e.g. ssh-copy-id-6.2p2.bottle.tar.gz
-    m = /(\d\.(\d)+(p(\d)+)?)/.match(stem)
+    # e.g. icu4c-52.1.bottle.tar.gz
+    m = /(\d+\.(\d)+(p(\d)+)?)/.match(stem)
     return m.captures.first unless m.nil?
 
     super

Library/Homebrew/test/test_bottle_versions.rb

@@ -15,4 +15,9 @@ class BottleVersionParsingTests < Test::Unit::TestCase
     assert_version_detected '6.2p2',
       '/usr/local/ssh-copy-id-6.2p2.mountain_lion.bottle.tar.gz'
   end
+
+  def test_icu4c_style
+    assert_version_detected '52.1',
+      '/usr/local/icu4c-52.1.bottle.tar.gz'
+  end
 end