Minor clean up to silence some gcc warnings.

Minor clean up to silence some gcc warnings.
* src/window.c (Fset_window_buffer):
* src/xterm.c (x_set_frame_alpha): Restructure code to silence
compiler warning.
(handle_one_xevent): Remove unused var `p'.
(do_ewmh_fullscreen): Remove unused var `lval'.
(xembed_set_info): Remove unused var `atom'.
* src/textprop.c (Fremove_list_of_text_properties): Add braces to silence
compiler warning.
* src/fontset.c (fontset_id_valid_p, dump_fontset):
* src/ftfont.c (ftfont_drive_otf): Modernize k&r declaration.
* src/eval.c (Feval, Ffuncall): Avoid unneeded gotos.
* src/dispnew.c (update_frame, update_frame_1): Compile the `do_pause'
label only when it's used.
* src/image.c (x_create_bitmap_from_xpm_data):
* src/dispextern.h (x_create_bitmap_from_xpm_data): Use const char** like
its callers.
* src/coding.c (detect_coding_utf_16): Remove unused vars `src_base' and
`consumed_chars'.
(DECODE_EMACS_MULE_21_COMPOSITION): Remove unused var `charbuf_base'.
(decode_coding_emacs_mule): Remove unused label `retry'.
(detect_eol): Add parens to silence compiler warning.
* src/alloc.c (bytes_used_when_reconsidered): Move to the #ifdef where
it's used to silence the compiler.
(make_number): Modernize k&r declaration.
(mark_char_table): Add parens to silence compiler warning.