Merge of various recorder changes from mythtv-rec2.

 * Fixes #9191. Channel switching doesn't work with cx18 driver.
 * Fixes #9451. IPTVRecorder doesn't produce proper TS packets for big DVB tables.
 * Fixes #9709. TFW IOBOUND.
 * This also fixes pause status locking in various recorders.
 * This also replaces a few spinlocks with QWaitConditions.
 * This also adds a DVB ASI recorder implementation in just 1033 lines. (Uninteresting to most).
 * This makes changes to the DeviceReadBuffer to make it more efficient and quicker to respond.
 * This changes the ThreadedFileWriter so that it can expand the level of buffering it does when there are temporary slowdowns in writing to disk.

This will probably cause some regressions, that's why I'm pushing this on a Monday. This refactors all the recorders and stream readers to eliminate a lot of duplicate code, and also fixes a number of small bugs and long time annoyances see the dkristjansson/mythtv-rec branch for details.

mythtv/configure

@@ -115,6 +115,7 @@ Advanced options (experts only):
   --dvb-path=HDRLOC        location of directory containing
                            'linux/dvb/frontend.h', not the
                            directory with frontend.h [$dvb_path_default]
+  --disable-asi            disable support for ASI recorder
   --disable-x11            disable X11 support
   --x11-path=X11LOC        location of X11 include files [$x11_path_default]
   --disable-xrandr         disable X11 resolution switching
@@ -1344,6 +1345,7 @@ MYTHTV_CONFIG_LIST='
     hdpvr
     iptv
     ivtv
+    asi
     joystick_menu
     libfftw3
     libmpeg2external
@@ -1773,6 +1775,7 @@ v4l_deps="backend linux_videodev_h linux_videodev2_h"
 vdpau_deps="opengl vdpau_vdpau_h vdpau_vdpau_x11_h"
 xrandr_deps="x11"
 xv_deps="x11"
+asi_deps="backend"
 
 <<BLOCKQUOTE
 # tests
@@ -1977,6 +1980,7 @@ enable hdhomerun
 enable hdpvr
 enable iptv
 enable ivtv
+enable asi
 enable lamemp3
 enable libass
 enable libxml2
@@ -3997,6 +4001,12 @@ int main(void) {
 }
 EOF
 
+enabled asi && check_cc <<EOF || disable asi
+#include <dveo/asi.h>
+#include <dveo/master.h>
+int main(void) { return 1; }
+EOF
+
 # Check that all MythTV build "requirements" are met:
 enabled lamemp3 && check_lib2 lame/lame.h lame_init -lmp3lame -lm ||
     die "ERROR! You must have the Lame MP3 encoding library installed to compile MythTV."
@@ -4444,6 +4454,7 @@ if enabled backend; then
   echo "DVB-S2 support            ${fe_can_2g_modulation-no}"
   echo "HDHomeRun support         ${hdhomerun-no}"
   echo "IPTV support              ${iptv-no}"
+  echo "ASI support               ${asi-no}"
 fi
 
 if enabled frontend; then