Adapt to rearranged NDK sysroot.

Soong didn't have any explicit references to these paths because it
depends directly on the modules, but the make side of the build still
needs to construct these paths explicitly.

I removed a bunch of dead code that made the fix less obvious while I
was here.

Bug: None
Test: treehugger
Change-Id: I1a283a3bc98a94fc5481c869b3b0a4eacf69d859

core/binary.mk

@@ -168,7 +168,6 @@ my_allow_undefined_symbols := true
 endif
 endif
 
-my_ndk_sysroot :=
 my_ndk_sysroot_include :=
 my_ndk_sysroot_lib :=
 my_api_level := 10000
@@ -183,11 +182,7 @@ ifneq ($(LOCAL_SDK_VERSION),)
   # Make sure we've built the NDK.
   my_additional_dependencies += $(SOONG_OUT_DIR)/ndk_base.timestamp
 
-  ifneq (,$(filter arm64 x86_64,$(my_arch)))
-    my_min_sdk_version := 21
-  else
-    my_min_sdk_version := $(MIN_SUPPORTED_SDK_VERSION)
-  endif
+  my_min_sdk_version := $(MIN_SUPPORTED_SDK_VERSION)
 
   # Historically we've just set up a bunch of symlinks in prebuilts/ndk to map
   # missing API levels to existing ones where necessary, but we're not doing
@@ -200,38 +195,19 @@ ifneq ($(LOCAL_SDK_VERSION),)
 
   my_ndk_crt_version := $(my_ndk_api)
 
-  my_ndk_hist_api := $(my_ndk_api)
-  ifeq ($(my_ndk_api),current)
-    # The last API level supported by the old prebuilt NDKs.
-    my_ndk_hist_api := 24
-  else
+  ifneq ($(my_ndk_api),current)
     my_api_level := $(my_ndk_api)
   endif
 
   my_ndk_source_root := \
       $(HISTORICAL_NDK_VERSIONS_ROOT)/$(LOCAL_NDK_VERSION)/sources
-  my_ndk_sysroot := \
-    $(HISTORICAL_NDK_VERSIONS_ROOT)/$(LOCAL_NDK_VERSION)/platforms/android-$(my_ndk_hist_api)/arch-$(my_arch)
   my_built_ndk := $(SOONG_OUT_DIR)/ndk
   my_ndk_triple := $($(LOCAL_2ND_ARCH_VAR_PREFIX)TARGET_NDK_TRIPLE)
   my_ndk_sysroot_include := \
       $(my_built_ndk)/sysroot/usr/include \
       $(my_built_ndk)/sysroot/usr/include/$(my_ndk_triple) \
-      $(my_ndk_sysroot)/usr/include \
 
-  # x86_64 is a multilib toolchain, so their libraries are
-  # installed in /usr/lib64. Aarch64, on the other hand, is not a multilib
-  # compiler, so its libraries are in /usr/lib.
-  ifneq (,$(filter x86_64,$(my_arch)))
-    my_ndk_libdir_name := lib64
-  else
-    my_ndk_libdir_name := lib
-  endif
-
-  my_ndk_platform_dir := \
-      $(my_built_ndk)/platforms/android-$(my_ndk_api)/arch-$(my_arch)
-  my_built_ndk_libs := $(my_ndk_platform_dir)/usr/$(my_ndk_libdir_name)
-  my_ndk_sysroot_lib := $(my_ndk_sysroot)/usr/$(my_ndk_libdir_name)
+  my_ndk_sysroot_lib := $(my_built_ndk)/sysroot/usr/lib/$(my_ndk_triple)/$(my_ndk_api)
 
   # The bionic linker now has support for packed relocations and gnu style
   # hashes (which are much faster!), but shipping to older devices requires
@@ -1428,7 +1404,6 @@ my_system_shared_libraries_fullpath := \
 my_ndk_shared_libraries_fullpath := \
     $(foreach _lib,$(my_ndk_shared_libraries),\
         $(if $(filter $(NDK_KNOWN_LIBS),$(_lib)),\
-            $(my_built_ndk_libs)/$(_lib)$(so_suffix),\
             $(my_ndk_sysroot_lib)/$(_lib)$(so_suffix)))
 
 built_shared_libraries += \