apps/include/opt.h: improve coding style #1210

Job	Run time
compiler (gcc-7, ubuntu-20.04)	4m 22s
compiler (gcc-8, ubuntu-20.04)	4m 22s
compiler (gcc-9, ubuntu-20.04)	4m 31s
compiler (gcc-10, ubuntu-20.04)	4m 21s
compiler (gcc-11, ubuntu-22.04)	4m 28s
compiler (gcc-12, ubuntu-22.04)	5m 6s
compiler (gcc-13, ubuntu-22.04, ubuntu-toolchain-r/test)	4m 54s
compiler (clang-6.0, ubuntu-20.04)	4m 46s
compiler (clang-7, ubuntu-20.04)	4m 38s
compiler (clang-8, ubuntu-20.04)	4m 49s
compiler (clang-9, ubuntu-20.04)	4m 48s
compiler (clang-10, ubuntu-20.04)	4m 52s
compiler (clang-11, ubuntu-20.04)	4m 44s
compiler (clang-12, ubuntu-20.04)	4m 45s
compiler (clang-13, ubuntu-22.04)	5m 13s
compiler (clang-14, ubuntu-22.04)	5m 6s
compiler (clang-15, ubuntu-22.04, jammy)	5m 15s
compiler (clang-16, ubuntu-22.04, jammy)	5m 43s
compiler (clang-17, ubuntu-22.04, jammy)	5m 31s
	1h 32m 14s

Provide feedback