libcamera: base: Fix log level parsing when multiple categories are

listed

For a list of log levels like LIBCAMERA_LOG_LEVELS="CatA:0,CatB:1" only
the severity of the last entry is correctly parsed.

Due to the change of level to a string_view in 24c2caa1c1 ("libcamera:
base: log: Use `std::string_view` to avoid some copies") the level is no
longer necessarily null terminated as it is a view on the original data.

Replace the check for a terminating null by a check for the end position
to fix the issue.

Fixes: 24c2caa1c1 ("libcamera: base: log: Use `std::string_view` to avoid some copies")
Signed-off-by: Stefan Klug <stefan.klug@ideasonboard.com>
Reviewed-by: Barnabás Pőcze <barnabas.pocze@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

test/log/meson.build

@@ -1,7 +1,7 @@
 # SPDX-License-Identifier: CC0-1.0
 
 log_test = [
-    {'name': 'log_api', 'sources': ['log_api.cpp'], 'should_fail': true},
+    {'name': 'log_api', 'sources': ['log_api.cpp']},
     {'name': 'log_process', 'sources': ['log_process.cpp']},
 ]