clear all caches before setting hints #527

Job	Run time
ubuntu-latest\|debug\|--enable-mcsat\|CC=gcc CXX=g++	9m 6s
ubuntu-latest\|debug\|--enable-mcsat\|CC=clang CXX=clang++	9m 28s
ubuntu-latest\|debug\|--enable-thread-safety\|CC=gcc CXX=g++	4m 11s
ubuntu-latest\|debug\|--enable-thread-safety\|CC=clang CXX=clang++	4m 42s
ubuntu-latest\|release\|--enable-mcsat\|CC=gcc CXX=g++	5m 54s
ubuntu-latest\|release\|--enable-mcsat\|CC=clang CXX=clang++	6m 20s
ubuntu-latest\|release\|--enable-thread-safety\|CC=gcc CXX=g++	2m 49s
ubuntu-latest\|release\|--enable-thread-safety\|CC=clang CXX=clang++	3m 16s
ubuntu-latest\|gcov\|--enable-mcsat\|CC=gcc CXX=g++	8m 45s
ubuntu-latest\|debug\|--enable-thread-safety --enable-mcsat\|CC=gcc CXX=g++	9m 19s
	1h 3m 50s

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