Remove extra definition of AIDL

AIDL is defined in the sometimes-prebuilt tools section, remove the
extra definition that was overriding it.

Change-Id: I677bf46475fd5fd4a9258c77d91ecee806e5f205
diff --git a/core/config.mk b/core/config.mk
index 1d7e9f3..597b0d7 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -499,7 +499,6 @@
 YASM := prebuilts/misc/$(BUILD_OS)-$(HOST_PREBUILT_ARCH)/yasm/yasm
 
 DOXYGEN:= doxygen
-AIDL := $(HOST_OUT_EXECUTABLES)/aidl$(HOST_EXECUTABLE_SUFFIX)
 AIDL_CPP := $(HOST_OUT_EXECUTABLES)/aidl-cpp$(HOST_EXECUTABLE_SUFFIX)
 ifeq ($(HOST_OS),linux)
 BREAKPAD_DUMP_SYMS := $(HOST_OUT_EXECUTABLES)/dump_syms