Implement __gnu_Unwind_Find_exidx/__cxa_type_match

Leaving these unimplemented causes linker to have 2 weak undefined
symbols which in turn results in 3 unwanted relocations for arm arch.
Implementing them removes unwanted relocations from resulted dynamic
object

Test: make && readelf --dyn-sym linker
Test: linker-unit-tests && bionic-unit-tests --gtest_filter=dl*:Dl*
Test: flash and boot angler
Change-Id: I10120271936c770659239898aaf852d31c5483c2
diff --git a/linker/Android.bp b/linker/Android.bp
index fda7eb5..6a4e2b9 100644
--- a/linker/Android.bp
+++ b/linker/Android.bp
@@ -39,7 +39,10 @@
 
     arch: {
         arm: {
-            srcs: ["arch/arm/begin.S"],
+            srcs: [
+                "arch/arm/begin.S",
+                "linker_exidx_static.c",
+            ],
 
             cflags: ["-D__work_around_b_24465209__"],
         },