FTL: Standardize style

Adopt STL-flavored Google style for internal and libbase consistency.

Add README.

Bug: 160012986
Test: ftl_test
Change-Id: I1056f6fa890d68717386d634c398bb2faa46775c
diff --git a/libs/ftl/Android.bp b/libs/ftl/Android.bp
index eb8e57a..883d138 100644
--- a/libs/ftl/Android.bp
+++ b/libs/ftl/Android.bp
@@ -5,9 +5,9 @@
         address: true,
     },
     srcs: [
-        "SmallMap_test.cpp",
-        "SmallVector_test.cpp",
-        "StaticVector_test.cpp",
+        "small_map_test.cpp",
+        "small_vector_test.cpp",
+        "static_vector_test.cpp",
     ],
     cflags: [
         "-Wall",