Eliminated all compiler warnings on Android

3rdparty/libtiff/CMakeLists.txt

@@ -88,6 +88,10 @@ endif()
 
 add_library(${the_target} STATIC ${lib_srcs} ${lib_hdrs})
 
+if(CMAKE_COMPILER_IS_GNUCXX)
+  set_source_files_properties(tif_stream.cxx PROPERTIES COMPILE_FLAGS "-Wno-sign-compare")
+endif()
+
 set_target_properties(${the_target}
 	PROPERTIES
 	OUTPUT_NAME "${the_target}"

modules/core/include/opencv2/core/operations.hpp

@@ -3655,12 +3655,13 @@ public:
     static int isInstance(const void* ptr)
     {
         static _ClsName dummy;
+        static void* dummyp = &dummy;
         union
         {
             const void* p;
             const void** pp;
         } a, b;
-        a.p = &dummy;
+        a.p = dummyp;
         b.p = ptr;
         return *a.pp == *b.pp;
     }

modules/objdetect/src/lsvmtbbversion.cpp

@@ -32,8 +32,8 @@ public:
                      CvPoint ****_partsDisplacement) :
     n(_n), b(_b), maxXBorder(_maxXBorder), 
         maxYBorder(_maxYBorder), scoreThreshold(_scoreThreshold),
-        kLevels(_kLevels), score(_score), points(_points), kPoints(_kPoints),
-        partsDisplacement(_partsDisplacement)
+        kLevels(_kLevels), score(_score), points(_points),
+        partsDisplacement(_partsDisplacement), kPoints(_kPoints)
     {
         filters = _filters;
         H = _H;