perf(mcache): no alloc

[xiaost]

goos: darwin
goarch: arm64
pkg: github.com/bytedance/gopkg/lang/mcache
                      │   ./old.out   │              ./new.out              │
                      │    sec/op     │    sec/op     vs base               │
MCache4096-12           26.270n ±  2%   9.533n ±  1%  -63.71% (p=0.002 n=6)
MCache10M-12            25.885n ±  2%   9.486n ±  0%  -63.36% (p=0.002 n=6)
MCache4096Parallel-12    105.3µ ± 17%   113.4µ ±  7%        ~ (p=0.065 n=6)
MCache10MParallel-12     123.7µ ±  5%   120.8µ ± 17%        ~ (p=0.310 n=6)
geomean                  1.725µ         1.055µ        -38.83%

                      │    ./old.out    │               ./new.out                │
                      │      B/op       │    B/op     vs base                    │
MCache4096-12               24.00 ±  0%    0.00 ± 0%  -100.00% (p=0.002 n=6)
MCache10M-12                27.50 ±  5%    0.00 ± 0%  -100.00% (p=0.002 n=6)
MCache4096Parallel-12     234.7Ki ± 23%   0.0Ki ± 0%  -100.00% (p=0.002 n=6)
MCache10MParallel-12    804424.50 ±  3%   74.50 ±  ?   -99.99% (p=0.002 n=6)
geomean                   3.282Ki                     ?                      ¹ ²
¹ summaries must be >0 to compute geomean
² ratios must be >0 to compute geomean

                      │  ./old.out   │               ./new.out                │
                      │  allocs/op   │ allocs/op   vs base                    │
MCache4096-12            1.000 ±  0%   0.000 ± 0%  -100.00% (p=0.002 n=6)
MCache10M-12             1.000 ±  0%   0.000 ± 0%  -100.00% (p=0.002 n=6)
MCache4096Parallel-12   10.00k ± 23%   0.00k ± 0%  -100.00% (p=0.002 n=6)
MCache10MParallel-12    32.48k ±  4%   0.00k ± 0%  -100.00% (p=0.002 n=6)
geomean                  134.3                     ?                      ¹ ²
¹ summaries must be >0 to compute geomean
² ratios must be >0 to compute geomean