Reduce the usage of strlen #1358

Job	Run time
Checks	5m 34s
Linux_x86-64_Build_Correctness_Debugger_Tests	5m 1s
Conformance_Tests_ESNext	2m 12s
Conformance_Tests_ESNext_Debug_B	1m 20s
Conformance_Tests_ESNext_Debug_A	2m 6s
Linux_x86_cpointer-32bit_Build_Correctness_Tests	1m 38s
Linux_x86-64_Build_Option_Tests	4m 29s
OSX_x86-64_Build_Correctness_Unit_Tests	1m 54s
OSX_x86-64_Build_Correctness_Unit_Tests_Debug	1m 55s
ASAN_Tests	3m 34s
ASAN_Tests_Debug	3m 40s
Clang_Unit_Build_Option_Tests	25s
Linux_AArch64_Tests_Debug	6m 51s
Linux_AArch64_Tests	4m 26s
Linux_ARMv7l_Tests	4m 34s
Linux_ARMv7l_Tests_Debug	6m 7s
MbedOS_K64F_Build_Test	1m 53s
NuttX_STM32F4_Build_Test	2m 14s
UBSAN_Tests	2m 16s
Unit_Tests	13s
Zephyr_STM32F4_Build_Test	3m 11s
ESP_IDF_Build_Test	3m 34s
ESP8266_RTOS_SDK_Build_Test	1m 30s
Notification	0s
RIOT_STM32F4_Build_Test	58s
	1h 11m 35s

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