Rename common to android

Rename the "common" package to "android", because common is too
generic.  Also removes all android.Android naming stutter.

Ran:
gomvpkg -from 'android/soong/common' -to 'android/soong/android'
gorename -from '"android/soong/android".AndroidModuleContext' -to 'ModuleContext'
gorename -from '"android/soong/android".AndroidBaseContext' -to 'BaseContext'
gorename -from '"android/soong/android".AndroidModuleBase' -to 'ModuleBase'
gorename -from '"android/soong/android".AndroidBottomUpMutatorContext' -to 'BottomUpMutatorContext'
gorename -from '"android/soong/android".AndroidTopDownMutatorContext' -to 'TopDownMutatorContext'
gorename -from '"android/soong/android".AndroidModule' -to 'Module'

Change-Id: I3b23590b8ce7c8a1ea1139411d84a53163288da7
diff --git a/android/util.go b/android/util.go
new file mode 100644
index 0000000..60c8a63
--- /dev/null
+++ b/android/util.go
@@ -0,0 +1,78 @@
+// Copyright 2015 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package android
+
+import "sort"
+
+func JoinWithPrefix(strs []string, prefix string) string {
+	if len(strs) == 0 {
+		return ""
+	}
+
+	if len(strs) == 1 {
+		return prefix + strs[0]
+	}
+
+	n := len(" ") * (len(strs) - 1)
+	for _, s := range strs {
+		n += len(prefix) + len(s)
+	}
+
+	ret := make([]byte, 0, n)
+	for i, s := range strs {
+		if i != 0 {
+			ret = append(ret, ' ')
+		}
+		ret = append(ret, prefix...)
+		ret = append(ret, s...)
+	}
+	return string(ret)
+}
+
+func JoinWithPrefixAndQuote(strs []string, prefix string) string {
+	if len(strs) == 0 {
+		return ""
+	}
+
+	if len(strs) == 1 {
+		return prefix + `"` + strs[0] + `"`
+	}
+
+	n := len(" ") * (len(strs) - 1)
+	for _, s := range strs {
+		n += len(prefix) + len(s) + len(`""`)
+	}
+
+	ret := make([]byte, 0, n)
+	for i, s := range strs {
+		if i != 0 {
+			ret = append(ret, ' ')
+		}
+		ret = append(ret, prefix...)
+		ret = append(ret, '"')
+		ret = append(ret, s...)
+		ret = append(ret, '"')
+	}
+	return string(ret)
+}
+
+func sortedKeys(m map[string][]string) []string {
+	s := make([]string, 0, len(m))
+	for k := range m {
+		s = append(s, k)
+	}
+	sort.Strings(s)
+	return s
+}