Use INCLUDE_DIRs for libraries. Simplify conditions

CMakeLists.txt

@@ -19,10 +19,14 @@ add_compile_definitions(PALETTE_DIR="../palettes")
 
 if (PNG_FOUND AND LIBSNDFILE_FOUND)
     add_executable(aptdec ${EXE_C_SOURCE_FILES})
-    target_link_libraries(aptdec PRIVATE libaptdec)
+    include_directories(${PNG_PNG_INCLUDE_DIR})
+    include_directories(${LIBSNDFILE_INCLUDE_DIR})
     target_link_libraries(aptdec PRIVATE PNG::PNG)
     target_link_libraries(aptdec PRIVATE ${LIBSNDFILE_LIBRARY})
-    if (CLANG OR GCC)
+    target_link_libraries(aptdec PRIVATE libaptdec)
+    if (MSVC)
+        target_compile_options(aptdec PRIVATE /D_CRT_SECURE_NO_WARNINGS=1)
+    else()
         # Math
         target_link_libraries(aptdec PRIVATE m)
 
@@ -32,21 +36,22 @@ if (PNG_FOUND AND LIBSNDFILE_FOUND)
         else()
             target_compile_options(aptdec PRIVATE -Wall -Wextra -pedantic)
         endif()
-    elseif (MSVC)
-        target_compile_options(aptdec PRIVATE /D_CRT_SECURE_NO_WARNINGS=1)
     endif()
 else()
     MESSAGE(STATUS "WARNING: Only building libaptdec, as not all of the required libraries were found.")
 endif()
 
-if (CLANG OR CGCC)
+if (MSVC)
+    target_compile_options(libaptdec PRIVATE /D_CRT_SECURE_NO_WARNINGS=1)
+else()
+    # Math
+    target_link_libraries(libaptdec PRIVATE m)
+
     if(CMAKE_BUILD_TYPE MATCHES "Release")
         target_compile_options(libaptdec PRIVATE -Wall -Wextra -pedantic -Wno-missing-field-initializers -Werror)
     else()
         target_compile_options(libaptdec PRIVATE -Wall -Wextra -pedantic)
     endif()
-elseif (MSVC)
-    target_compile_options(libaptdec PRIVATE /D_CRT_SECURE_NO_WARNINGS=1)
 endif()
 
 # TODO: get this from git