Handle properly stringifying multiline macro expressions #13122

Job	Run time
check_format	1m 34s
x86_64-gnu-test-preview_mt	5m 41s
x86_64-musl-test	37m 24s
x86_64-gnu-test (1.7.3)	33m 23s
x86_64-gnu-test (1.8.2)	34m 31s
x86_64-gnu-test (1.9.2)	34m 2s
x86_64-gnu-test (1.10.1)	34m 25s
x86_64-gnu-test (1.11.2)	32m 43s
x86_64-gnu-test (1.12.2)	33m 18s
x86_64-gnu-test (1.13.3)	31m 55s
x86_64-gnu-test (1.14.0)	32m 11s
x86_64-gnu-test (1.0.0, FLAGS=-Dwithout_ffi USE_PCRE1=true)	32m 37s
x86_64-gnu-test (1.1.1, FLAGS=-Dwithout_ffi USE_PCRE1=true)	32m 43s
x86_64-gnu-test (1.2.2, USE_PCRE1=true)	33m 36s
x86_64-gnu-test (1.3.2, USE_PCRE1=true)	34m 33s
x86_64-gnu-test (1.4.1, USE_PCRE1=true)	32m 51s
x86_64-gnu-test (1.5.1, USE_PCRE1=true)	33m 2s
x86_64-gnu-test (1.6.2, USE_PCRE1=true)	32m 41s
	9h 3m 10s

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