Fix cgroup2 "max" case #11635

When $MAX == "max", there is no limit on the cpu usage set
Use multiprocessing.cpu_count() function in that case

conan/tools/build/cpu.py

@@ -16,15 +16,15 @@ def _cpu_count():
     try:
         try:
             # This is necessary to deduce docker cpu_count
+            cfs_quota_us = cfs_period_us = 0
             # cgroup2
             if os.path.exists("/sys/fs/cgroup/cgroup.controllers"):
                 cpu_max = load("/sys/fs/cgroup/cpu.max").split()
-                if cpu_max[0] == "max":
-                    return 1
-                elif len(cpu_max) == 1:
-                    cfs_quota_us, cfs_period_us = int(cpu_max[0]), 1
-                else:
-                    cfs_quota_us, cfs_period_us = map(int, cpu_max)
+                if cpu_max[0] != "max":
+                    if len(cpu_max) == 1:
+                        cfs_quota_us, cfs_period_us = int(cpu_max[0]), 100_000
+                    else:
+                        cfs_quota_us, cfs_period_us = map(int, cpu_max)
             else:  # cgroup1
                 cfs_quota_us = int(load("/sys/fs/cgroup/cpu/cpu.cfs_quota_us"))
                 cfs_period_us = int(load("/sys/fs/cgroup/cpu/cpu.cfs_period_us"))