Fix some warnings from -O0 build

modules/core/src/precomp.hpp

@@ -94,7 +94,7 @@ template<typename T1, typename T2=T1, typename T3=T1> struct OpAdd
     typedef T1 type1;
     typedef T2 type2;
     typedef T3 rtype;
-    T3 operator ()(T1 a, T2 b) const { return saturate_cast<T3>(a + b); }
+    T3 operator ()(const T1 a, const T2 b) const { return saturate_cast<T3>(a + b); }
 };
 
 template<typename T1, typename T2=T1, typename T3=T1> struct OpSub
@@ -102,7 +102,7 @@ template<typename T1, typename T2=T1, typename T3=T1> struct OpSub
     typedef T1 type1;
     typedef T2 type2;
     typedef T3 rtype;
-    T3 operator ()(T1 a, T2 b) const { return saturate_cast<T3>(a - b); }
+    T3 operator ()(const T1 a, const T2 b) const { return saturate_cast<T3>(a - b); }
 };
 
 template<typename T1, typename T2=T1, typename T3=T1> struct OpRSub
@@ -110,7 +110,7 @@ template<typename T1, typename T2=T1, typename T3=T1> struct OpRSub
     typedef T1 type1;
     typedef T2 type2;
     typedef T3 rtype;
-    T3 operator ()(T1 a, T2 b) const { return saturate_cast<T3>(b - a); }
+    T3 operator ()(const T1 a, const T2 b) const { return saturate_cast<T3>(b - a); }
 };
 
 template<typename T> struct OpMin
@@ -118,7 +118,7 @@ template<typename T> struct OpMin
     typedef T type1;
     typedef T type2;
     typedef T rtype;
-    T operator ()(T a, T b) const { return std::min(a, b); }
+    T operator ()(const T a, const T b) const { return std::min(a, b); }
 };
 
 template<typename T> struct OpMax
@@ -126,7 +126,7 @@ template<typename T> struct OpMax
     typedef T type1;
     typedef T type2;
     typedef T rtype;
-    T operator ()(T a, T b) const { return std::max(a, b); }
+    T operator ()(const T a, const T b) const { return std::max(a, b); }
 };
 
 inline Size getContinuousSize( const Mat& m1, int widthScale=1 )

modules/imgproc/src/morph.cpp

@@ -56,7 +56,7 @@ template<typename T> struct MinOp
     typedef T type1;
     typedef T type2;
     typedef T rtype;
-    T operator ()(T a, T b) const { return std::min(a, b); }
+    T operator ()(const T a, const T b) const { return std::min(a, b); }
 };
 
 template<typename T> struct MaxOp
@@ -64,7 +64,7 @@ template<typename T> struct MaxOp
     typedef T type1;
     typedef T type2;
     typedef T rtype;
-    T operator ()(T a, T b) const { return std::max(a, b); }
+    T operator ()(const T a, const T b) const { return std::max(a, b); }
 };
 
 #undef CV_MIN_8U
@@ -72,8 +72,8 @@ template<typename T> struct MaxOp
 #define CV_MIN_8U(a,b)       ((a) - CV_FAST_CAST_8U((a) - (b)))
 #define CV_MAX_8U(a,b)       ((a) + CV_FAST_CAST_8U((b) - (a)))
 
-template<> inline uchar MinOp<uchar>::operator ()(uchar a, uchar b) const { return CV_MIN_8U(a, b); }
-template<> inline uchar MaxOp<uchar>::operator ()(uchar a, uchar b) const { return CV_MAX_8U(a, b); }
+template<> inline uchar MinOp<uchar>::operator ()(const uchar a, const uchar b) const { return CV_MIN_8U(a, b); }
+template<> inline uchar MaxOp<uchar>::operator ()(const uchar a, const uchar b) const { return CV_MAX_8U(a, b); }
 
 struct MorphRowNoVec
 {