Clean up libutils Android.mk

Removed LOCAL_C_INCLUDES as the external/zlib headers are no longer
referenced by anything in libutils.

Removed unused host_commonLdlibs build variable. This was referenced
by the lib64utils host target which was removed in commit 03cc1f747

Tested compiling some of the projects that make use of libcutils
using a clean out dir with the folllowing targets

aosp_arm-eng : make -j16 logd dexdump
aosp-flouder-userdebug : make -j16 keystore vold libjavacore logd
aosp-x86_64-eng : make -j16 keystore vold libjavacore logd dexdump

Change-Id: I663e52bbf28dde27866dad9429bf95ada6b594a5
diff --git a/libutils/Android.mk b/libutils/Android.mk
index e738c15..52de910 100644
--- a/libutils/Android.mk
+++ b/libutils/Android.mk
@@ -53,13 +53,6 @@
 endif
 endif
 
-host_commonLdlibs :=
-
-ifeq ($(TARGET_OS),linux)
-host_commonLdlibs += -lrt -ldl
-endif
-
-
 # For the host
 # =====================================================
 include $(CLEAR_VARS)
@@ -93,9 +86,6 @@
 endif
 LOCAL_CFLAGS += -Werror
 
-LOCAL_C_INCLUDES += \
-	external/zlib
-
 LOCAL_STATIC_LIBRARIES := \
 	libcutils