v.builder: fix cross compiling from linux to windows with `-os window… #7272

Job	Run time
tests-sanitize-address-clang	2h 1m 32s
tests-sanitize-address-gcc	2h 31m 37s
tests-sanitize-address-msvc	3m 32s
tests-sanitize-memory-clang	3h 16m 50s
tests-sanitize-undefined-clang	59m 26s
tests-sanitize-undefined-gcc	1h 31m 44s
	10h 24m 41s

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