Fix cmake detection of build platform endianness

Improve comments to indicate actual usage of WORDS_BIGENDIAN where
it is tested with #ifdef rather than #if

3rdparty/libtiff/CMakeLists.txt

@@ -6,7 +6,6 @@ project(${TIFF_LIBRARY})
 
 include(CheckFunctionExists)
 include(CheckIncludeFile)
-include(TestBigEndian)
 
 check_include_file(assert.h HAVE_ASSERT_H)
 check_include_file(fcntl.h HAVE_FCNTL_H)
@@ -17,7 +16,6 @@ check_include_file(search.h HAVE_SEARCH_H)
 check_include_file(string.h HAVE_STRING_H)
 check_include_file(sys/types.h HAVE_SYS_TYPES_H)
 check_include_file(unistd.h HAVE_UNISTD_H)
-test_big_endian(HOST_BIGENDIAN)
 
 if(WIN32 AND NOT HAVE_WINRT)
   set(USE_WIN32_FILEIO 1)

3rdparty/libtiff/tif_config.h.cmakein

@@ -54,7 +54,7 @@
 
 /* Native cpu byte order: 1 if big-endian (Motorola) or 0 if little-endian
    (Intel) */
-#define HOST_BIGENDIAN @HOST_BIGENDIAN@
+#define HOST_BIGENDIAN @WORDS_BIGENDIAN@
 
 /* Set the native cpu bit order (FILLORDER_LSB2MSB or FILLORDER_MSB2LSB) */
 #define HOST_FILLORDER FILLORDER_LSB2MSB
@@ -154,17 +154,9 @@
 /* define to use win32 IO system */
 #cmakedefine USE_WIN32_FILEIO
 
-/* Define WORDS_BIGENDIAN to 1 if your processor stores words with the most
+/* Define WORDS_BIGENDIAN if your processor stores words with the most
    significant byte first (like Motorola and SPARC, unlike Intel). */
-#if defined AC_APPLE_UNIVERSAL_BUILD
-# if defined __BIG_ENDIAN__
-#  define WORDS_BIGENDIAN 1
-# endif
-#else
-# ifndef WORDS_BIGENDIAN
-/* #  undef WORDS_BIGENDIAN */
-# endif
-#endif
+#cmakedefine WORDS_BIGENDIAN
 
 /* Support Deflate compression */
 #define ZIP_SUPPORT 1

CMakeLists.txt

@@ -444,6 +444,12 @@ endif()
 include(cmake/OpenCVPCHSupport.cmake)
 include(cmake/OpenCVModule.cmake)
 
+# ----------------------------------------------------------------------------
+#  Detect endianness of build platform
+# ----------------------------------------------------------------------------
+include(TestBigEndian)
+test_big_endian(WORDS_BIGENDIAN)
+
 # ----------------------------------------------------------------------------
 #  Detect 3rd-party libraries
 # ----------------------------------------------------------------------------

cmake/templates/cvconfig.h.in

@@ -161,6 +161,6 @@
 /* Xine video library */
 #cmakedefine HAVE_XINE
 
-/* Define to 1 if your processor stores words with the most significant byte
+/* Define if your processor stores words with the most significant byte
    first (like Motorola and SPARC, unlike Intel and VAX). */
 #cmakedefine WORDS_BIGENDIAN