Use (1L << feature)' instead of (1 << feature)' to avoid problems

with integer overflows when we add more fields.

sysdeps/kernel/procsignal.c

@@ -27,10 +27,10 @@
 #include <glibtop_private.h>
 
 static const unsigned long _glibtop_sysdeps_proc_signal =
-(1 << GLIBTOP_PROC_SIGNAL_SIGNAL) +
-(1 << GLIBTOP_PROC_SIGNAL_BLOCKED) +
-(1 << GLIBTOP_PROC_SIGNAL_SIGIGNORE) +
-(1 << GLIBTOP_PROC_SIGNAL_SIGCATCH);
+(1L << GLIBTOP_PROC_SIGNAL_SIGNAL) +
+(1L << GLIBTOP_PROC_SIGNAL_BLOCKED) +
+(1L << GLIBTOP_PROC_SIGNAL_SIGIGNORE) +
+(1L << GLIBTOP_PROC_SIGNAL_SIGCATCH);
 
 /* Init function. */