remove the root build.rs #1037

Job	Run time
b3sum Linux GNU stable	17s
Linux GNU stable	1m 26s
b3sum Linux GNU beta	25s
build for Apple Silicon	26s
build with the Tiny C Compiler	14s
Linux GNU beta	1m 39s
b3sum Linux GNU nightly	20s
Linux GNU nightly	1m 36s
b3sum Linux GNU 1.70.0	22s
Linux GNU 1.66.1	3m 53s
b3sum macOS stable	22s
C Makefile tests	1m 35s
CMake ubuntu-latest gcc	14s
macOS stable	2m 22s
b3sum macOS beta	27s
CMake ubuntu-latest clang	5s
macOS beta	3m 1s
b3sum macOS nightly	45s
CMake ubuntu-latest cl	5s
cross i586-unknown-linux-musl	1m 26s
b3sum macOS 1.70.0	52s
cross i686-unknown-linux-musl	1m 36s
CMake macOS-latest gcc	19s
macOS nightly	2m 49s
b3sum Windows MSVC stable	1m 13s
cross armv7-unknown-linux-gnueabihf	1m 40s
b3sum Windows MSVC beta	49s
CMake macOS-latest clang	10s
cross aarch64-unknown-linux-gnu	1m 43s
b3sum Windows MSVC nightly	51s
macOS 1.66.1	6m 25s
CMake macOS-latest cl	17s
cross powerpc64-unknown-linux-gnu	1m 34s
b3sum Windows MSVC 1.70.0	44s
Windows MSVC stable	3m 37s
CMake windows-latest clang	48s
cross s390x-unknown-linux-gnu	1m 31s
Windows MSVC beta	2m 39s
CMake windows-latest cl	1m 6s
b3sum Windows GNU stable	1m 0s
Windows MSVC nightly	2m 46s
b3sum Windows GNU beta	58s
compile and test with GCC 5.4	1m 0s
Windows MSVC 1.66.1	5m 4s
b3sum Windows GNU nightly	50s
Windows GNU stable	3m 21s
b3sum Windows GNU 1.70.0	59s
Windows GNU beta	3m 10s
Windows GNU nightly	3m 11s
Windows GNU 1.66.1	6m 58s
	1h 21m 0s

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