Add `Crystal::HOST_TRIPLE` and `TARGET_TRIPLE` (#13823) #2462

Job	Run time
deploy_api_docs	0s
check_format	1m 44s
x86_64-gnu-test (1.7.3)	42m 20s
x86_64-gnu-test-preview_mt	8m 10s
x86_64-gnu-test (1.8.2)	40m 31s
x86_64-musl-test	53m 46s
x86_64-gnu-test (1.9.2)	40m 50s
x86_64-gnu-test (1.10.1)	31m 5s
x86_64-gnu-test (1.0.0, FLAGS=-Dwithout_ffi USE_PCRE1=true)	36m 7s
x86_64-gnu-test (1.1.1, FLAGS=-Dwithout_ffi USE_PCRE1=true)	46m 49s
x86_64-gnu-test (1.2.2, USE_PCRE1=true)	53m 23s
x86_64-gnu-test (1.3.2, USE_PCRE1=true)	40m 40s
x86_64-gnu-test (1.4.1, USE_PCRE1=true)	47m 39s
x86_64-gnu-test (1.5.1, USE_PCRE1=true)	42m 55s
x86_64-gnu-test (1.6.2, USE_PCRE1=true)	53m 8s
	8h 59m 7s

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