Fix #106040: pasting long text fails in Gnome-Shell/Wayland

Workaround gnome-shell including uninitialized memory when pasting
from the clipboard. Where `read` woud

Reading from the pipe into a power-of-two buffer
works around the problem.

It's not clear why this only impacts gnome-shell - as there is no
significant down-side to changing the buffer size, apply a workaround.

intern/ghost/intern/GHOST_SystemWayland.cpp

@@ -2016,7 +2016,13 @@ static char *read_file_as_buffer(const int fd, const bool nil_terminate, size_t
 {
   struct ByteChunk {
     ByteChunk *next;
-    char data[4096 - sizeof(ByteChunk *)];
+    /* NOTE(@ideasman42): On GNOME-SHELL-43.3, non powers of two values
+     * (1023 or 4088 for e.g.) makes `read()` return longer values than are actually read
+     * (causing uninitialized memory to be used) as well as truncating the end of the buffer.
+     * The WAYLAND spec doesn't mention buffer-size so this may be a bug in GNOME-SHELL.
+     * Whatever the case, using a power of two isn't a problem (besides some slop-space waste).
+     * This works in KDE & WLROOTS based compositors, see: #106040. */
+    char data[4096];
   };
   ByteChunk *chunk_first = nullptr, **chunk_link_p = &chunk_first;
   bool ok = true;