cmake: Added find_package module for fontconfig which is not available with cmake < 3.14

This file has been taken from cmake 3.14

CMakeModules/FindFontconfig.cmake

@@ -0,0 +1,101 @@
+# Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+# file Copyright.txt or https://cmake.org/licensing for details.
+
+#[=======================================================================[.rst:
+FindFontconfig
+--------------
+
+Find Fontconfig headers and library.
+
+Imported Targets
+^^^^^^^^^^^^^^^^
+
+``Fontconfig::Fontconfig``
+  The Fontconfig library, if found.
+
+Result Variables
+^^^^^^^^^^^^^^^^
+
+This will define the following variables in your project:
+
+``FONTCONFIG_FOUND``
+  true if (the requested version of) Fontconfig is available.
+``FONTCONFIG_VERSION``
+  the version of Fontconfig.
+``FONTCONFIG_LIBRARIES``
+  the libraries to link against to use Fontconfig.
+``FONTCONFIG_INCLUDE_DIRS``
+  where to find the Fontconfig headers.
+``FONTCONFIG_COMPILE_OPTIONS``
+  this should be passed to target_compile_options(), if the
+  target is not used for linking
+
+#]=======================================================================]
+
+
+# use pkg-config to get the directories and then use these values
+# in the FIND_PATH() and FIND_LIBRARY() calls
+find_package(PkgConfig QUIET)
+pkg_check_modules(PKG_FONTCONFIG QUIET fontconfig)
+set(FONTCONFIG_COMPILE_OPTIONS ${PKG_FONTCONFIG_CFLAGS_OTHER})
+set(FONTCONFIG_VERSION ${PKG_FONTCONFIG_VERSION})
+
+find_path( FONTCONFIG_INCLUDE_DIR
+  NAMES
+    fontconfig/fontconfig.h
+  HINTS
+    ${PKG_FONTCONFIG_INCLUDE_DIRS}
+    /usr/X11/include
+)
+
+find_library( FONTCONFIG_LIBRARY
+  NAMES
+    fontconfig
+  PATHS
+    ${PKG_FONTCONFIG_LIBRARY_DIRS}
+)
+
+if (FONTCONFIG_INCLUDE_DIR AND NOT FONTCONFIG_VERSION)
+  file(STRINGS ${FONTCONFIG_INCLUDE_DIR}/fontconfig/fontconfig.h _contents REGEX "^#define[ \t]+FC_[A-Z]+[ \t]+[0-9]+$")
+  unset(FONTCONFIG_VERSION)
+  foreach(VPART MAJOR MINOR REVISION)
+    foreach(VLINE ${_contents})
+      if(VLINE MATCHES "^#define[\t ]+FC_${VPART}[\t ]+([0-9]+)$")
+        set(FONTCONFIG_VERSION_PART "${CMAKE_MATCH_1}")
+        if(FONTCONFIG_VERSION)
+          string(APPEND FONTCONFIG_VERSION ".${FONTCONFIG_VERSION_PART}")
+        else()
+          set(FONTCONFIG_VERSION "${FONTCONFIG_VERSION_PART}")
+        endif()
+      endif()
+    endforeach()
+  endforeach()
+endif ()
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(Fontconfig
+  FOUND_VAR
+    FONTCONFIG_FOUND
+  REQUIRED_VARS
+    FONTCONFIG_LIBRARY
+    FONTCONFIG_INCLUDE_DIR
+  VERSION_VAR
+    FONTCONFIG_VERSION
+)
+
+
+if(FONTCONFIG_FOUND AND NOT TARGET Fontconfig::Fontconfig)
+  add_library(Fontconfig::Fontconfig UNKNOWN IMPORTED)
+  set_target_properties(Fontconfig::Fontconfig PROPERTIES
+    IMPORTED_LOCATION "${FONTCONFIG_LIBRARY}"
+    INTERFACE_COMPILE_OPTIONS "${FONTCONFIG_COMPILE_OPTIONS}"
+    INTERFACE_INCLUDE_DIRECTORIES "${FONTCONFIG_INCLUDE_DIR}"
+  )
+endif()
+
+mark_as_advanced(FONTCONFIG_LIBRARY FONTCONFIG_INCLUDE_DIR)
+
+if(FONTCONFIG_FOUND)
+  set(FONTCONFIG_LIBRARIES ${FONTCONFIG_LIBRARY})
+  set(FONTCONFIG_INCLUDE_DIRS ${FONTCONFIG_INCLUDE_DIR})
+endif()

src/osgText/CMakeLists.txt

@@ -1,4 +1,4 @@
-find_package(Fontconfig MODULE QUIET)
+find_package(Fontconfig MODULE)
 
 IF(DYNAMIC_OPENSCENEGRAPH)
     ADD_DEFINITIONS(-DOSGTEXT_LIBRARY)