Add DwarfSection classes.

Bug: 23762183

Test: Ran new unit tests.
Change-Id: Icca2a73c50d467718ba4ac41e1c8f541488620dd
diff --git a/libunwindstack/Android.bp b/libunwindstack/Android.bp
index 32ed6c3..eb2b902 100644
--- a/libunwindstack/Android.bp
+++ b/libunwindstack/Android.bp
@@ -50,6 +50,7 @@
         "DwarfCfa.cpp",
         "DwarfMemory.cpp",
         "DwarfOp.cpp",
+        "DwarfSection.cpp",
         "Elf.cpp",
         "ElfInterface.cpp",
         "ElfInterfaceArm.cpp",
@@ -98,6 +99,8 @@
         "tests/DwarfMemoryTest.cpp",
         "tests/DwarfOpLogTest.cpp",
         "tests/DwarfOpTest.cpp",
+        "tests/DwarfSectionTest.cpp",
+        "tests/DwarfSectionImplTest.cpp",
         "tests/ElfInterfaceArmTest.cpp",
         "tests/ElfInterfaceTest.cpp",
         "tests/ElfTest.cpp",
@@ -123,6 +126,10 @@
         "liblog",
     ],
 
+    static_libs: [
+        "libgmock",
+    ],
+
     target: {
         linux: {
             host_ldlibs: [