Update VERSIONs to 3.7-rc2 for release. #184

Job	Run time
build (gcc, 3.12, 3.3)	1m 32s
build (gcc, 3.12, 3.3, test-flags-override)	1m 22s
build (gcc, 3.12, 3.3, test-debug)	1m 25s
build (gcc, 3.12, 3.3, linker-bfd)	1m 34s
build (gcc, 3.12, 3.3, linker-gold)	1m 39s
build (gcc, 3.11, 3.3)	1m 29s
build (gcc, 3.10, 3.3)	2m 8s
build (gcc, 3.9, 3.3)	1m 36s
build (gcc, 3.8, 3.3)	1m 44s
build (gcc, 3.7, 3.3)	1m 48s
build (gcc, pypy3.7, 3.3)	1m 59s
build (gcc, 3.12, 3.2)	1m 36s
build (gcc, 3.12, 3.1)	1m 42s
build (gcc, 3.12, 3.0)	1m 37s
build (gcc, 3.12, 2.7)	2m 19s
build (gcc, 3.12, 2.6)	1m 45s
build (gcc, 3.12, 2.5)	1m 43s
build (clang, 3.12, 3.3)	1m 43s
build (clang, 3.12, 3.3, test-flags-override)	1m 37s
build (clang, 3.12, 3.3, test-debug)	1m 29s
build (clang, 3.11, 3.3)	1m 39s
build (clang, 3.10, 3.3)	2m 29s
build (clang, 3.9, 3.3)	1m 44s
build (clang, 3.8, 3.3)	1m 46s
build (clang, 3.7, 3.3)	1m 59s
build (clang, pypy3.7, 3.3)	2m 17s
build (clang, 3.12, 3.2)	1m 41s
build (clang, 3.12, 3.1)	1m 44s
build (clang, 3.12, 3.0)	1m 43s
build (clang, 3.12, 2.7)	1m 59s
build (clang, 3.12, 2.6)	1m 48s
build (clang, 3.12, 2.5)	1m 51s
build (gcc, 3.12, 3.3, sanitizers)	2m 12s
	58m 39s

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