Don't pack relocations in libc.so

Ic9125cc1bc4c9ba9eb20d030de72e3ce1fb86fa6 disabled relocation packing
in libc.so, but the flag was dropped when we switched to Android.bp
in Ib0ba2d28bff88483b505426ba61606da314e03ab.

Bug: 20645321
Bug: 20655855
Bug: 32750616
Test: builds
Test: inspect out/build-aosp_angler.ninja
Test: run app that crashes with packed libc.so
Change-Id: Ib0630f2e342afa543bb88303fec8f9695ac583e9
diff --git a/libc/Android.bp b/libc/Android.bp
index 00932de..f326db3 100644
--- a/libc/Android.bp
+++ b/libc/Android.bp
@@ -1649,6 +1649,9 @@
         keep_symbols: true,
     },
 
+    // Do not pack libc.so relocations; see http://b/20645321 for details.
+    pack_relocations: false,
+
     // WARNING: The only library libc.so should depend on is libdl.so!  If you add other libraries,
     // make sure to add -Wl,--exclude-libs=libgcc.a to the LOCAL_LDFLAGS for those libraries.  This
     // ensures that symbols that are pulled into those new libraries from libgcc.a are not declared