fix: support pkg-config

Signed-off-by: Henry Schreiner <henryschreineriii@gmail.com>

Author: henryiii

cmake/FindGD.cmake

@@ -1,12 +1,19 @@
+find_package(PkgConfig)
+if(PKG_CONFIG_FOUND)
+  pkg_check_modules(PC_GD QUIET GD)
+endif()
 
-find_path (GD_INCLUDE_DIR
-           "gd.h"
-           REQUIRED)
+find_path(GD_INCLUDE_DIR
+  NAMES gd.h
+  HINTS "${PC_GD_INCLUDE_DIRS}"
+  REQUIRED
+)
 
-find_library (GD_LIBRARY
-              gd
-              REQUIRED
-              )
+find_library(GD_LIBRARY
+  NAMES gd
+  HINTS "${PC_GD_INCLUDE_DIRS}"
+  REQUIRED
+)
 
 cmake_path(ABSOLUTE_PATH GD_LIBRARY)
 cmake_path(ABSOLUTE_PATH GD_INCLUDE_DIR)
@@ -24,12 +31,14 @@ find_package_handle_standard_args(GD
 if(GD_FOUND)
   set(GD_LIBRARIES "${GD_LIBRARY}")
   set(GD_INCLUDE_DIRS "${GD_INCLUDE_DIR}")
+  set(Foo_DEFINITIONS ${PC_GD_CFLAGS_OTHER})
 endif()
 
 if(GD_FOUND AND NOT TARGET GD::GD)
   add_library(GD::GD UNKNOWN IMPORTED)
   set_target_properties(GD::GD PROPERTIES
     IMPORTED_LOCATION "${GD_LIBRARY}"
+    INTERFACE_COMPILE_OPTIONS "${PC_GD_CFLAGS_OTHER}"
     INTERFACE_INCLUDE_DIRECTORIES "${GD_INCLUDE_DIR}"
   )
 endif()