bionic: linker-unit-tests: Add crt_pad_segment tests

Test crt_pad_segment note parsing.

Test: atest -c linker-unit-tests
Bug: 316403210
Bug: 300367402
Bug: 307803052
Bug: 312550202
Change-Id: I0a7db8113a8b1df72696906bdd48a6ab6b6715f7
diff --git a/linker/linker_test_globals.cpp b/linker/linker_test_globals.cpp
index 33a78b0..4b41eed 100644
--- a/linker/linker_test_globals.cpp
+++ b/linker/linker_test_globals.cpp
@@ -29,3 +29,8 @@
 // To enable logging
 int g_ld_debug_verbosity = 0;
 
+// Stub some symbols to avoid linking issues
+void DL_WARN_documented_change(int api_level [[maybe_unused]],
+                               const char* doc_link [[maybe_unused]],
+                               const char* fmt [[maybe_unused]], ...) {}
+