[config] Many updates to configuration and feature checks

- Added custom checks for libraries and pkgconfig modules that test library
 presence with additional checks for use of headers and functions with
 given options.  Also support correct additional feature library checks
 using provided flags.
- Added custom enable/disable feature macros to simplify their use.
- Use custom CFLAGS and LIBS variables for Makefiles to simplify maintenance.
- Update many feature checks from platform to function.
- Streamline many function checks.
- Correctly check gnutls, gcrypt and gpg-error libraries.
- Fix chromecast and spotify config and compile on FreeBSD
- Added inotify, signalfd and kqueue, and byte swap checks.
- Many clarifications of error messages.
- Correct json-c checks to properly use supplied CFLAGS.
- Correct many quoting inconsistencies
- Use __DATE__ in place of BUILDDATE
- Use full path for gperf and antlr3
- Remove unnecessary CFLAGS
- Added tests for pthread_setname_np parameters
- Added tests for clock_gettime and timer_settime
- Added tests for time.h
- Test if pthread, dl and rt libs are required/available.
- Updated checks for libunistring

src/main.c

@@ -39,7 +39,7 @@
 
 #ifdef HAVE_SIGNALFD
 # include <sys/signalfd.h>
-#elif defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
+#else
 # include <sys/time.h>
 # include <sys/event.h>
 #endif
@@ -374,7 +374,7 @@ signal_signalfd_cb(int fd, short event, void *arg)
     event_add(sig_event, NULL);
 }
 
-#elif defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
+#else
 
 static void
 signal_kqueue_cb(int fd, short event, void *arg)
@@ -468,7 +468,7 @@ main(int argc, char **argv)
   const char *gcry_version;
   sigset_t sigs;
   int sigfd;
-#if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
+#ifdef HAVE_KQUEUE
   struct kevent ke_sigs[4];
 #endif
   int ret;
@@ -607,14 +607,14 @@ main(int argc, char **argv)
 #ifdef MPD
   strcat(buildopts, " --enable-mpd");
 #endif
-#ifdef ALSA
+#ifdef HAVE_ALSA
   strcat(buildopts, " --with-alsa");
 #endif
-#ifdef PULSEAUDIO
+#ifdef HAVE_LIBPULSE
   strcat(buildopts, " --with-pulseaudio");
 #endif
 
-  DPRINTF(E_LOG, L_MAIN, "Built %s with:%s\n", BUILDDATE, buildopts);
+  DPRINTF(E_LOG, L_MAIN, "Built %s with:%s\n", __DATE__, buildopts);
 
   ret = av_lockmgr_register(ffmpeg_lockmgr);
   if (ret < 0)
@@ -825,7 +825,7 @@ main(int argc, char **argv)
     }
 
   sig_event = event_new(evbase_main, sigfd, EV_READ, signal_signalfd_cb, NULL);
-#elif defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
+#else
   sigfd = kqueue();
   if (sigfd < 0)
     {