Make android_get_application_target_sdk_version available to the NDK.

Also move this and android_get_device_api_level into <android/api-level.h>
so that they're always available.

This involves cleaning up <sys/cdefs.h> slightly.

Bug: N/A
Test: builds
Change-Id: I25435c55f3549cd0d827a7581bee75ea8228028b
diff --git a/libdl/libdl.mips.map b/libdl/libdl.mips.map
index 8d4019c..a03e9e1 100644
--- a/libdl/libdl.mips.map
+++ b/libdl/libdl.mips.map
@@ -30,6 +30,7 @@
 
 LIBC_N {
   global:
+    android_get_application_target_sdk_version; # introduced=24 versioned=29
     dlvsym; # introduced=24
 } LIBC;
 
@@ -44,7 +45,6 @@
   global:
     __cfi_init;
     android_dlwarning;
-    android_get_application_target_sdk_version;
     android_set_application_target_sdk_version;
     android_get_LD_LIBRARY_PATH;
     android_update_LD_LIBRARY_PATH;