speed up cppcheck

linters/tox.ini

@@ -9,6 +9,7 @@ changedir = /src
 [testenv:cppcheck]
 whitelist_externals = cppcheck
 commands = cppcheck \
+			-j4 \
 			--force \
 			--std=c11 \
 			--error-exitcode=1 \
@@ -19,7 +20,7 @@ commands = cppcheck \
 			--inline-suppr \
 			--library=python \
 			--include=linters/cppcheck.h \
-		src python/ustreamer.c janus/rtp.h janus/rtp.c janus/plugin.c
+		src python/*.? janus/*.?
 
 [testenv:flake8]
 whitelist_externals = bash