Use INSTALL_PATH in cmake call

This ensures that backend libraries  are copied into dpctl
and included in the conda tar ball.

Also fixed copy statement to account for .lib files being
in %INSTALL_PREFIX%\lib and .dll files being in
%INSTALL_PREFIX%\bin on Windows.

Author: oleksandr-pavlyk

conda-recipe/bld.bat

@@ -17,7 +17,7 @@ rmdir /S /Q "%INSTALL_PREFIX%"
 
 cmake -G Ninja ^
     -DCMAKE_BUILD_TYPE=Release ^
-    "-DCMAKE_INSTALL_PREFIX=%LIBRARY_PREFIX%" ^
+    "-DCMAKE_INSTALL_PREFIX=%INSTALL_PREFIX%" ^
     "-DCMAKE_PREFIX_PATH=%LIBRARY_PREFIX%" ^
     "-DDPCPP_ROOT=%DPCPP_ROOT%" ^
     "%SRC_DIR%/backends"
@@ -29,7 +29,7 @@ IF %ERRORLEVEL% NEQ 0 exit 1
 
 cd ..
 xcopy install\lib\*.lib dpctl /E /Y
-xcopy install\lib\*.dll dpctl /E /Y
+xcopy install\bin\*.dll dpctl /E /Y
 
 mkdir dpctl\include
 xcopy backends\include dpctl\include /E /Y