rename all "support" parameters; avoid new compiler warnings

rename all "support" parameters; avoid new compiler warnings

Change each occurrence like this (which evokes a warning from gcc):
-	return *supported = MAX_TOTAL_PART;
to this:
+	*max_n = MAX_TOTAL_PART;
+	return true;

I did it mostly mechanically:

  cd libparted/labels &&
    grep -l 'return .supported = ' *.c|xargs perl -ni \
      -e '$m=/^\treturn \*supported( = .*;)/;' \
      -e 'print $m ? "\t*max_n$1\n\treturn true;\n" : $_'
  git grep -l 'int\* supported'|xargs perl -pi -e 's/int\* supported/int *max_n/'

That got all but aix.c, which used different spacing: "int *supported",
which I changed manually.  Then I updated all copyright dates.