MJPEG Tools Svn

remove unused variable res

y4mtoqt.c:314:6: variable res set but not used

properly conditionalize the vectorscope variables to avoid these warnings:

y4mhist.c:481:14: warning: variable pheight set but not used
y4mhist.c:481:6: warning: variable pwidth set but not used
y4mhist.c:480: warning: variable do_vectorscope set but not used
y4mhist.c:479:21: variable ss_h set but not used
y4mhist.c:479:15: warning: ss_v set but not used

need to have SDLgfx which apparently few systems have anymore - so those
variables aren't needed most of the time

remove unused variable

y4mshift.c:227:25: warning: variable H2 set but not used

remove variables identified by:

y4munsharp.c:447:23: warning: variable cmatrix_p set but not used
y4munsharp.c:545:21: warning: variable matrix_midpoint set but not used

unused variables were producing warning errors:

encode.c:950:9⚠️ variable noisy_sbs set but not used
encode.c:990:9⚠️ variable noisy_sbs set but not used
musicin.c:176:9⚠️ variable mono set but not used
musicin.c:175:9⚠️ variable stereo set but not used

Once the unused variables were removed it was noticed that the return values
of two functions were always ignored - these could be changed to void().

sumtop_acc and sumbot_acc set but never used. removed

if pointer is null don't compar it to a 0 character

gcc 7 saw that a height_pad was set twice but never used. variable is
remove

bump micro version number - the repository version now differs from the 2.2.0
release in the download area.

remove fallback check for libpng 1.2 - if libpng can't be found don't look for
a version that's so old.

Remove incorrect tag