CMake: Properly declare target include directories for generated incl…

…udes.

Previously the non targeted `include_directories()` was used, which had
issue when using the `png_static` target in a submodule.

CMakeLists.txt

@@ -362,8 +362,6 @@ else()
   message(STATUS "Could not find an AWK-compatible program")
 endif()
 
-include_directories(${CMAKE_CURRENT_BINARY_DIR})
-
 if(NOT AWK OR ANDROID OR IOS)
   # No awk available to generate sources; use pre-built pnglibconf.h
   configure_file(${CMAKE_CURRENT_SOURCE_DIR}/scripts/pnglibconf.h.prebuilt
@@ -714,6 +712,8 @@ if(PNG_SHARED)
   endif()
   target_include_directories(png_shared
                              PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>)
+  target_include_directories(png_shared
+                             PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_BINARY_DIR}>)
   target_include_directories(png_shared SYSTEM
                              INTERFACE $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}/libpng${PNGLIB_ABI_VERSION}>)
   target_link_libraries(png_shared PUBLIC ZLIB::ZLIB ${M_LIBRARY})
@@ -728,6 +728,8 @@ if(PNG_STATIC)
                         DEBUG_POSTFIX "${PNG_DEBUG_POSTFIX}")
   target_include_directories(png_static
                              PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}>)
+  target_include_directories(png_static
+                             PUBLIC $<BUILD_INTERFACE:${CMAKE_CURRENT_BINARY_DIR}>)
   target_include_directories(png_static SYSTEM
                              INTERFACE $<INSTALL_INTERFACE:${CMAKE_INSTALL_INCLUDEDIR}/libpng${PNGLIB_ABI_VERSION}>)
   target_link_libraries(png_static PUBLIC ZLIB::ZLIB ${M_LIBRARY})