-  Fix building on OpenBSD
   94aed7a1011ef48e6524fb16bfb7dfb025dc0746

- Fix includes
- Honor CFLAGS and DEBUG
- Use system libpng on arm platforms

Index: CMakeLists.txt
--- CMakeLists.txt.orig
+++ CMakeLists.txt
@@ -258,6 +258,9 @@ if(MACOSX AND NOT IOS)
 	endif()
 endif()
 
+include_directories(${X11BASE}/include)
+include_directories(${LOCALBASE}/lib/libzip/include)
+
 include(FindThreads)
 
 if(APPLE)
@@ -358,13 +361,13 @@ if(NOT MSVC)
 		endif()
 	endif()
 
-	set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -g -D_DEBUG")
+	set(CMAKE_CXX_FLAGS_DEBUG "${CMAKE_CXX_FLAGS_DEBUG} -D_DEBUG")
 	set(CMAKE_CXX_FLAGS_MINSIZEREL "${CMAKE_CXX_FLAGS_MINSIZEREL} -Os -D_NDEBUG")
-	set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -O2 -D_NDEBUG")
+	set(CMAKE_CXX_FLAGS_RELEASE "${CMAKE_CXX_FLAGS_RELEASE} -D_NDEBUG")
 	set(CMAKE_CXX_FLAGS_RELWITHDEBINFO "${CMAKE_CXX_FLAGS_RELWITHDEBINFO} -O2 -g -D_NDEBUG")
-	set(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG} -g -D_DEBUG")
+	set(CMAKE_C_FLAGS_DEBUG "${CMAKE_C_FLAGS_DEBUG} -D_DEBUG")
 	set(CMAKE_C_FLAGS_MINSIZEREL "${CMAKE_C_FLAGS_MINSIZEREL} -Os -D_NDEBUG")
-	set(CMAKE_C_FLAGS_RELEASE "${CMAKE_C_FLAGS_RELEASE} -O2 -D_NDEBUG")
+	set(CMAKE_C_FLAGS_RELEASE "${CMAKE_C_FLAGS_RELEASE} -D_NDEBUG")
 	set(CMAKE_C_FLAGS_RELWITHDEBINFO "${CMAKE_C_FLAGS_RELWITHDEBINFO} -O2 -g -D_NDEBUG")
 
 	# Enable checking printf-like format strings (also works for logging functions)
@@ -404,7 +407,7 @@ if(NOT MSVC)
 			add_definitions(-Wno-psabi)
 		endif()
 		add_definitions(-D_XOPEN_SOURCE=700)
-		add_definitions(-D_XOPEN_SOURCE_EXTENDED -D__BSD_VISIBLE=1)
+		add_definitions(-D_XOPEN_SOURCE_EXTENDED -D__BSD_VISIBLE=1 -D_BSD_SOURCE)
 		add_definitions(-D_LARGEFILE64_SOURCE=1 -D_FILE_OFFSET_BITS=64)
 	elseif(ANDROID)
 		add_definitions(-fsigned-char)
@@ -933,6 +936,7 @@ endif()
 find_package(LIBZIP)
 if(LIBZIP_FOUND AND USE_SYSTEM_LIBZIP)
 	add_definitions(-DSHARED_LIBZIP)
+	include_directories(${LIBZIP_INCLUDE_DIRS})
 else()
 	add_library(libzip STATIC
 		ext/libzip/zip_add.c
@@ -1070,7 +1074,7 @@ else()
 endif()
 
 # Arm platforms require at least libpng17.
-if(ANDROID OR ARMV7 OR ARM64 OR ARM OR IOS)
+if(ANDROID OR IOS)
 	set(PNG_REQUIRED_VERSION 1.7)
 else()
 	set(PNG_REQUIRED_VERSION 1.6)