tests: simplify test_customized_mnem.c a little bit
tests: simplify test_customized_mnem.c a little bit

xia0pin9/capstone,fvrmatteo/capstone,AmesianX/capstone,bSr43/capstone,AmesianX/capstone,fvrmatteo/capstone,AmesianX/capstone,AmesianX/capstone,fvrmatteo/capstone,bSr43/capstone,xia0pin9/capstone,bSr43/capstone,bSr43/capstone,xia0pin9/capstone,fvrmatteo/capstone,bSr43/capstone,xia0pin9/capstone,fvrmatteo/capstone,AmesianX/capstone,xia0pin9/capstone,AmesianX/capstone,fvrmatteo/capstone,fvrmatteo/capstone,bSr43/capstone,AmesianX/capstone,bSr43/capstone,xia0pin9/capstone,xia0pin9/capstone