RISCV64-CI: don't rely on dependency resolution for qemu-user #6238

Job	Run time
build (macos-latest, gfortran, make)	12m 21s
msys2 (UCRT64, int64, Release)	16m 29s
build (ubuntu-latest, gfortran, cmake)	45m 46s
msys2 (MINGW32, int32, Release)	15m 59s
msys2 (CLANG64, int64, Release)	17m 51s
build (ubuntu-latest, gfortran, make)	22m 56s
build (macos-latest, gfortran, cmake)	21m 5s
build (ubuntu-latest, flang, make)	6m 6s
cross_build (mipsel, mipsel-linux-gnu, TARGET=MIPS1004K)	4m 7s
msys2 (UCRT64, int32, Release)	15m 20s
cross_build (riscv64, riscv64-linux-gnu, TARGET=RISCV64_GENERIC)	2m 21s
msys2 (UCRT64, int32, None, mingw-w64-ucrt-x86_64, fc)	15m 44s
cross_build (alpha, alpha-linux-gnu, TARGET=EV4)	3m 6s
cross_build (mips64el, mips64el-linux-gnuabi64, DYNAMIC_ARCH=1 TARGET=GENERIC)	3m 57s
neoverse_build	7m 47s
msys2 (CLANG64, int32, Release)	19m 1s
build (ubuntu-latest, flang, cmake)	13m 0s
	4h 2m 56s

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