Fix rm command for class cleanup in r7091

In https://webrtc-codereview.appspot.com/20339004
the rm command was missing 'r' for recursive mode.

TBR=henrike@webrtc.org
BUG=

Review URL: https://webrtc-codereview.appspot.com/26379004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@7092 4adac7df-926f-26a2-2b94-8c16560cd09d
diff --git a/webrtc/webrtc_examples.gyp b/webrtc/webrtc_examples.gyp
index 02888d5..8d8e227 100644
--- a/webrtc/webrtc_examples.gyp
+++ b/webrtc/webrtc_examples.gyp
@@ -130,7 +130,7 @@
               'outputs': ['<(PRODUCT_DIR)/OpenSlDemo-debug.apk'],
               'action': [
                 'bash', '-ec',
-                'rm -f <(_outputs) <(android_opensl_demo_root)/{bin,libs} && '
+                'rm -fr <(_outputs) <(android_opensl_demo_root)/{bin,libs} && '
                 'mkdir -p <(android_opensl_demo_root)/libs/<(android_app_abi) && '
                 'mkdir -p <(INTERMEDIATE_DIR) && ' # Must happen _before_ the cd below
                 '<(android_strip) -o <(android_opensl_demo_root)/libs/<(android_app_abi)/libopensl-demo-jni.so <(PRODUCT_DIR)/libopensl-demo-jni.so && '