A video4linux framegrabber Code

Fix compiler warnings

v_writer.c: In function ‘write_jpeg’:
v_writer.c:63:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
v_writer.c: In function ‘write_png’:
v_writer.c:108:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]

Fix compiler warnings

v_writer.c: In function ‘write_jpeg’:
v_writer.c:59:13: warning: pointer targets in assignment differ in signedness [-Wpointer-sign]
v_writer.c: In function ‘write_png’:
v_writer.c:110:22: warning: pointer targets in assignment differ in signedness [-Wpointer-sign]

Fix compiler warning

v_utils.c: In function ‘check_maxlen’:
v_utils.c:324:48: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]

Fix compiler warnings

v_utils.c: In function ‘switch_color’:
v_utils.c:135:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
v_utils.c: In function ‘conv_rgb32_rgb24’:
v_utils.c:148:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]

Correctly check v4l1_mmap() returned value

v_utils.c: In function ‘init_mmap’:
v_utils.c:30:94: warning: ordered comparison of pointer with integer zero [-Wextra]

Fix compiler warnings

v_utils.c: In function ‘check_minmax’:
v_utils.c:310:97: warning: declaration of ‘l_opt’ shadows a global declaration [-Wshadow]
In file included from v_utils.h:24:0,
from v_utils.c:24:
vgrabbj.h:309:25: warning: shadowed declaration is here [-Wshadow]
v_utils.c: In function ‘check_maxlen’:
v_utils.c:321:73: warning: declaration of ‘l_opt’ shadows a global declaration [-Wshadow]
In file included from v_utils.h:24:0,
from v_utils.c:24:
vgrabbj.h:309:25: warning: shadowed declaration is here [-Wshadow]

Fix compiler warnings

vgrabbj.c: In function ‘conv_image’:
vgrabbj.c:314:20: warning: pointer targets in assignment differ in signedness [-Wpointer-sign]
vgrabbj.c:350:20: warning: pointer targets in assignment differ in signedness [-Wpointer-sign]
vgrabbj.c: In function ‘main’:
vgrabbj.c:380:22: warning: pointer targets in assignment differ in signedness [-Wpointer-sign]
vgrabbj.c:383:22: warning: pointer targets in assignment differ in signedness [-Wpointer-sign]

Fix compiler warning

vgrabbj.c: In function ‘conv_image’:
vgrabbj.c:302:15: warning: comparison between signed and unsigned
integer expressions [-Wsign-compare]

Fix compiler warning

vgrabbj.c: In function ‘conv_image’:
vgrabbj.c:353:3: warning: pointer targets in return differ in signedness
[-Wpointer-sign]

Fix compiler warning

vgrabbj.c: In function ‘read_image’:
vgrabbj.c:287:3: warning: pointer targets in return differ in signedness
[-Wpointer-sign]