Enable libc/libdl/libm/linker for host bionic

Disables debuggerd integration unless building for android.

Bug: 31559095
Test: Diff out/soong/build.ninja before/after, only change is moving
      linker's libdebuggerd_client static lib to the beginning of the
      list.
Test: lunch aosp_arm64-eng; mmma -j bionic
Change-Id: I62e725f7a9b98b7fe31637d0a835fd5846b0aff0
diff --git a/linker/linker_main.cpp b/linker/linker_main.cpp
index 2e98bf0..a8cc814 100644
--- a/linker/linker_main.cpp
+++ b/linker/linker_main.cpp
@@ -40,7 +40,9 @@
 
 #include "android-base/strings.h"
 #include "android-base/stringprintf.h"
+#ifdef __ANDROID__
 #include "debuggerd/client.h"
+#endif
 
 #include <vector>
 
@@ -217,6 +219,7 @@
   __system_properties_init(); // may use 'environ'
 
   // Register the debuggerd signal handler.
+#ifdef __ANDROID__
   debuggerd_callbacks_t callbacks = {
     .get_abort_message = []() {
       return g_abort_message;
@@ -224,6 +227,7 @@
     .post_dump = &notify_gdb_of_libraries,
   };
   debuggerd_init(&callbacks);
+#endif
 
   g_linker_logger.ResetState();