libct/system/proc_test: fix, improve, add benchmark
libct/system/proc_test: fix, improve, add benchmark

1. Add a test case that tests parentheses in command.

2. Replace individual comparisons with reflect.DeepEqual.
   This also fixes wrong %-style types in Fatalf statements.

3. Replace Fatalf with Errorf so we don't bail out on the first
   failure, and do not check result on error.

4. Add two benchmarks. On my laptop, they show:

BenchmarkParseStat-4       	  116415	     10804 ns/op
BenchmarkParseRealStat-4   	     240	   4781769 ns/op

Signed-off-by: Kir Kolyshkin <3a017b8ddb3f9cf3e4a59978b004111bdeb97f08@gmail.com>

kolyshkin/runc,kolyshkin/runc,opencontainers/runc,opencontainers/runc,kolyshkin/runc,opencontainers/runc,opencontainers/runc,rhatdan/runc,rhatdan/runc,rhatdan/runc,rhatdan/runc,kolyshkin/runc