title: pthread error in ndk-build
body: <p>Hi</p>
  
  <p>I had try to compile the following Android.mk file using ndk-build.</p>
  
  <p>I got the following errors. how can I resolve this problem?</p>
  
  <p>please help me.</p>
  
  <p>the make file is</p>
  
  <pre><code># ================================================== ========
  # NOTE:
  # when executing binary, set LD_LIBRARY_PATH in device
  # ================================================== ========
  
  LOCAL_PATH := $(call my-dir)
  
  include $(CLEAR_VARS)
  
  BASEDIR := ../../..
  DISTDIR := ../../../..
  
  LOCAL_MODULE := EvaluateFingerQuality
  
  LOCAL_ARM_MODE := arm
  
  
  # Includes
  LOCAL_C_INCLUDES += \
  $(BASEDIR)/Common/C \
  $(DISTDIR)/Include
  
  # Source files
  LOCAL_SRC_FILES := \
  $(BASEDIR)/Common/C/Utils.c \
  EvaluateFingerQuality.c
  
  
  LOCAL_LDLIBS += \
  -Wl,-z,muldefs -Wl,-rpath=$(DISTDIR)/Lib/Android_$(TARGET_ARCH_ABI) \
  -L $(DISTDIR)/Lib/Android_$(TARGET_ARCH_ABI) \
  -lNLicensing -lNBiometricTools -lNBiometrics -lNMedia -lNCore -lc
  
  include $(BUILD_EXECUTABLE)
  </code></pre>
  
  <p>the error is</p>
  
  <pre><code>$ ndk-build
  Compile arm : EvaluateFingerQuality &lt;= Utils.c
  Compile arm : EvaluateFingerQuality &lt;= EvaluateFingerQuality.c
  Executable : EvaluateFingerQuality
  ../../../../Lib/Android_armeabi/libNCore.so: undefined reference to `pthread_rwlock_trywrlock'
  ../../../../Lib/Android_armeabi/libNCore.so: undefined reference to `pthread_rwlock_rdlock'
  ../../../../Lib/Android_armeabi/libNCore.so: undefined reference to `pthread_rwlock_tryrdlock'
  ../../../../Lib/Android_armeabi/libNCore.so: undefined reference to `pthread_rwlock_wrlock'
  ../../../../Lib/Android_armeabi/libNCore.so: undefined reference to `dladdr'
  ../../../../Lib/Android_armeabi/libNCore.so: undefined reference to `pthread_rwlock_destroy'
  ../../../../Lib/Android_armeabi/libNCore.so: undefined reference to `pthread_rwlock_init'
  ../../../../Lib/Android_armeabi/libNCore.so: undefined reference to `pthread_rwlock_unlock'
  collect2: ld returned 1 exit status
  /cygdrive/d/android-ndk-r8-windows/android-ndk-r8/build/core/build-binary.mk:381: recipe for target `/cygdrive/d/MegaMatcher_Embedded_1_2_SDK_Trial_for_Android/Tutorials/BiometricTools/C/obj/local/armeabi/EvaluateFingerQuality' failed
  make: *** [/cygdrive/d/MegaMatcher_Embedded_1_2_SDK_Trial_for_Android/Tutorials/BiometricTools/C/obj/local/armeabi/EvaluateFingerQuality] Error 1
  </code></pre>