title: android ndk-build error
body: <p>I am trying to build tesseract for android.
  I have put tesseract in samples folder as </p>
  
  <p><code>C:\Android_NDK\android-ndk-r8\samples\tesseract</code> 
  with in <code>tesseract</code> folder I have <code>tesseract-3.00</code> folder, <code>leptonlib-1.66</code> folder and <code>libjpeg</code> folder.
  Whenever I try to build the code using ndk-build.
  I get error as </p>
  
  <p><code>C:/Android_NDK/android-ndk-r8/build/core/build-binary.mk:240: *** target pattern
   contains no '%'. Stop.</code></p>
  
  <p>I use ndk-build like this in Command Prompt
  <code>C:\Android_NDK\android-ndk-r8\samples\tesseract\jni&gt;C:\Android_NDK\android-ndk-r8/ndk-build</code></p>
  
  <p><code>Application.mk</code> file contents in tesseract/jni  folder<br>
      <code># ARMv7 is significanly faster due to the use of the hardware FPU<br>
       APP_STL := gnustl_static<br>
       APP_ABI := armeabi armeabi-v7a<br>
       APP_OPTIM := release<br>
       APP_CPPFLAGS += -fexceptions -frtti</code>    </p>
  
  <pre><code> Android.mk file contents in tesseract/jni folder  
  # NOTE: You must set these variables to their respective source paths before
  # compiling. For example, set LEPTONICA_PATH to the directory containing
  # the Leptonica configure file and source folders. Directories must be
  # root-relative, e.g. TESSERACT_PATH := /home/username/tesseract-3.00
  #
  # To set the variables, you can run the following shell commands:
  # export TESSERACT_PATH=&lt;path-to-tesseract&gt;
  # export LEPTONICA_PATH=&lt;path-to-leptonica&gt;
  # export LIBJPEG_PATH=&lt;path-to-libjpeg&gt;
  #
  # Or you can fill out and uncomment the following definitions:
  # TESSERACT_PATH := &lt;path-to-tesseract&gt;
  # LEPTONICA_PATH := &lt;path-to-leptonica&gt;
  # LIBJPEG_PATH := &lt;path-to-libjpeg&gt;
  
  ifeq "$(TESSERACT_PATH)" ""
    $(error You must set the TESSERACT_PATH variable to the Tesseract source \
        directory. See README and jni/Android.mk for details)
  endif
  
  ifeq "$(LEPTONICA_PATH)" ""
    $(error You must set the LEPTONICA_PATH variable to the Leptonica source \
        directory. See README and jni/Android.mk for details)
  endif
  
  ifeq "$(LIBJPEG_PATH)" ""
    $(error You must set the LIBJPEG_PATH variable to the Android JPEG \
        source directory. See README and jni/Android.mk for details)
  endif
  
  # Just build the Android.mk files in the subdirs
  include $(call all-subdir-makefiles) $(LIBJPEG_PATH)/Android.mk
  </code></pre>
  
  <p>Tried with Cygwin but the same problem.</p>
  
  <p>Looking forward to your reply.</p>
  
  <p>thanks.</p>