Add the Dwarf CFA handling.

Bug: 23762183

Test: Ran new unit tests.
Change-Id: I31abac1238cc671b78a505da655fb6298be072b4
diff --git a/libunwindstack/Android.bp b/libunwindstack/Android.bp
index 05d0353..32ed6c3 100644
--- a/libunwindstack/Android.bp
+++ b/libunwindstack/Android.bp
@@ -47,6 +47,7 @@
 
     srcs: [
         "ArmExidx.cpp",
+        "DwarfCfa.cpp",
         "DwarfMemory.cpp",
         "DwarfOp.cpp",
         "Elf.cpp",
@@ -92,6 +93,8 @@
     srcs: [
         "tests/ArmExidxDecodeTest.cpp",
         "tests/ArmExidxExtractTest.cpp",
+        "tests/DwarfCfaLogTest.cpp",
+        "tests/DwarfCfaTest.cpp",
         "tests/DwarfMemoryTest.cpp",
         "tests/DwarfOpLogTest.cpp",
         "tests/DwarfOpTest.cpp",