cmake: fix install path

CMake doesn't work with empty paths ("") or paths which contains "./"

cmake/OpenCVUtils.cmake

@@ -84,14 +84,10 @@ macro(ocv_check_environment_variables)
   endforeach()
 endmacro()
 
-macro(ocv_path_join result_var P1 P2)
-  string(REGEX REPLACE "^[/]+" "" P2 "${P2}")
-  if("${P1}" STREQUAL "")
-    if("${P2}" STREQUAL "")
-      set(${result_var} ".")
-    else()
-      set(${result_var} "${P2}")
-    endif()
+macro(ocv_path_join result_var P1 P2_)
+  string(REGEX REPLACE "^[/]+" "" P2 "${P2_}")
+  if("${P1}" STREQUAL "" OR "${P1}" STREQUAL ".")
+    set(${result_var} "${P2}")
   elseif("${P1}" STREQUAL "/")
     set(${result_var} "/${P2}")
   elseif("${P2}" STREQUAL "")
@@ -99,6 +95,11 @@ macro(ocv_path_join result_var P1 P2)
   else()
     set(${result_var} "${P1}/${P2}")
   endif()
+  string(REGEX REPLACE "([/\\]?)[\\.][/\\]" "\\1" ${result_var} "${${result_var}}")
+  if("${${result_var}}" STREQUAL "")
+    set(${result_var} ".")
+  endif()
+  #message(STATUS "'${P1}' '${P2_}' => '${${result_var}}'")
 endmacro()
 
 # rename modules target to world if needed