cpupower: avoid multiple definition with gcc -fno-common

Building cpupower with -fno-common in CFLAGS results in errors due to
multiple definitions of the 'cpu_count' and 'start_time' variables.

./utils/idle_monitor/snb_idle.o:./utils/idle_monitor/cpupower-monitor.h:28:
multiple definition of `cpu_count';
./utils/idle_monitor/nhm_idle.o:./utils/idle_monitor/cpupower-monitor.h:28:
first defined here
...
./utils/idle_monitor/cpuidle_sysfs.o:./utils/idle_monitor/cpuidle_sysfs.c:22:
multiple definition of `start_time';
./utils/idle_monitor/amd_fam14h_idle.o:./utils/idle_monitor/amd_fam14h_idle.c:85:
first defined here

The -fno-common option will be enabled by default in GCC 10.

Bug: https://bugs.gentoo.org/707462
Signed-off-by: Mike Gilbert <floppym@gentoo.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/power/cpupower/utils/idle_monitor/amd_fam14h_idle.c

@@ -82,7 +82,7 @@ static struct pci_access *pci_acc;
 static struct pci_dev *amd_fam14h_pci_dev;
 static int nbp1_entered;
 
-struct timespec start_time;
+static struct timespec start_time;
 static unsigned long long timediff;
 
 #ifdef DEBUG

tools/power/cpupower/utils/idle_monitor/cpuidle_sysfs.c

@@ -19,7 +19,7 @@ struct cpuidle_monitor cpuidle_sysfs_monitor;
 
 static unsigned long long **previous_count;
 static unsigned long long **current_count;
-struct timespec start_time;
+static struct timespec start_time;
 static unsigned long long timediff;
 
 static int cpuidle_get_count_percent(unsigned int id, double *percent,

tools/power/cpupower/utils/idle_monitor/cpupower-monitor.c

@@ -27,6 +27,8 @@ struct cpuidle_monitor *all_monitors[] = {
 0
 };
 
+int cpu_count;
+
 static struct cpuidle_monitor *monitors[MONITORS_MAX];
 static unsigned int avail_monitors;
 

tools/power/cpupower/utils/idle_monitor/cpupower-monitor.h

@@ -25,7 +25,7 @@
 #endif
 #define CSTATE_DESC_LEN 60
 
-int cpu_count;
+extern int cpu_count;
 
 /* Hard to define the right names ...: */
 enum power_range_e {