Don't use unavailable C99 long double math functions

uClibc variants do not provide the C99 long double math functions like ceill,
powl, etc.. For future compatibility use check_symbol_exists() to check
whether these functions are available, and keep the result in
HAVE_MATH_C99_LONG_DOUBLE. Use that instead of the fragile Cygwin version
check in triodef.h.

Fixes build failures under uClibc(-ng) like:

../../libwinpr/utils/libwinpr-utils.so.0.1.0: undefined reference to `powl'
../../libwinpr/utils/libwinpr-utils.so.0.1.0: undefined reference to `fmodl'
../../libwinpr/utils/libwinpr-utils.so.0.1.0: undefined reference to `ceill'
../../libwinpr/utils/libwinpr-utils.so.0.1.0: undefined reference to `log10l'
../../libwinpr/utils/libwinpr-utils.so.0.1.0: undefined reference to `floorl'
collect2: error: ld returned 1 exit status

Signed-off-by: Baruch Siach <baruch@tkos.co.il>

CMakeLists.txt

@@ -456,6 +456,9 @@ if(UNIX OR CYGWIN)
 	endif()
 	check_include_files(sys/timerfd.h HAVE_TIMERFD_H)
 	check_include_files(poll.h HAVE_POLL_H)
+	list(APPEND CMAKE_REQUIRED_LIBRARIES m)
+	check_symbol_exists(ceill math.h HAVE_MATH_C99_LONG_DOUBLE)
+	list(REMOVE_ITEM CMAKE_REQUIRED_LIBRARIES m)
 	set(X11_FEATURE_TYPE "RECOMMENDED")
 	set(WAYLAND_FEATURE_TYPE "RECOMMENDED")
 else()

config.h.in

@@ -46,6 +46,7 @@
 #cmakedefine WITH_WIN8
 #cmakedefine WITH_RDPSND_DSOUND
 #cmakedefine WITH_EVENTFD_READ_WRITE
+#cmakedefine HAVE_MATH_C99_LONG_DOUBLE
 
 #cmakedefine WITH_FFMPEG
 #cmakedefine WITH_GSTREAMER_1_0

winpr/libwinpr/utils/trio/triodef.h

@@ -313,25 +313,12 @@ typedef void * trio_pointer_t;
 # define TRIO_COMPILER_SUPPORTS_LL
 #endif
 
-#if defined(__CYGWIN__)
-/*
- * Cygwin defines the macros for hosted C99, but does not support certain
- * long double math functions.
- */
-# include <cygwin/version.h>
-# define TRIO_CYGWIN_VERSION_API CYGWIN_VERSION_API_MAJOR * 1000 + \
-   CYGWIN_VERSION_API_MINOR
-/*
- * Please change the version number below when the Cygwin API supports
- * long double math functions (powl, fmodl, etc.)
- */
-# if TRIO_CYGWIN_VERSION_API < 99999999
-#  define TRIO_NO_FLOORL 1
-#  define TRIO_NO_CEILL 1
-#  define TRIO_NO_POWL 1
-#  define TRIO_NO_FMODL 1
-#  define TRIO_NO_LOG10L 1
-# endif
+#if !defined(HAVE_MATH_C99_LONG_DOUBLE)
+# define TRIO_NO_FLOORL 1
+# define TRIO_NO_CEILL 1
+# define TRIO_NO_POWL 1
+# define TRIO_NO_FMODL 1
+# define TRIO_NO_LOG10L 1
 #endif
 
 #endif /* TRIO_TRIODEF_H */