Declare the headers of the ndk_library

This creates a dependency edge between the ndk_library and its headers,
which should be a no-op in regular Soong builds. This dependency edge
will be used in the Multi-tree project to export the relevant .h files into a well
known location

Test: m nothing
Bug: 239044713
Change-Id: I3f38edfbb8ce6b47dd4e73de4e1e0ad7a371799c
diff --git a/libc/Android.bp b/libc/Android.bp
index b216863..14eb3bb 100644
--- a/libc/Android.bp
+++ b/libc/Android.bp
@@ -2322,6 +2322,16 @@
     first_version: "9",
     // APIs implemented in asm don't have debug info: http://b/190554910.
     allow_untyped_symbols: true,
+    export_header_libs: [
+        "common_libc",
+        "libc_uapi",
+        "libc_kernel_android_uapi_linux",
+        "libc_kernel_android_scsi",
+        "libc_asm_arm",
+        "libc_asm_arm64",
+        "libc_asm_x86",
+        "libc_asm_x86_64",
+    ],
 }
 
 ndk_library {