lapacke_mangling.h is no longer generated, so don't delete on make clean #5566

Job	Run time
msys2 (UCRT64, int64, Release)	15m 36s
msys2 (UCRT64, int32, Release)	13m 28s
neoverse_build	8m 7s
msys2 (CLANG64, int64, Release)	17m 15s
msys2 (MINGW32, int32, Release)	17m 10s
msys2 (CLANG64, int32, Release)	16m 58s
msys2 (UCRT64, int32, None, mingw-w64-ucrt-x86_64, fc)	11m 39s
cross_build (riscv64, riscv64-linux-gnu, TARGET=RISCV64_GENERIC)	2m 37s
build (ubuntu-latest, gfortran, make)	21m 12s
build (ubuntu-latest, flang, make)	17m 34s
cross_build (mipsel, mipsel-linux-gnu, TARGET=MIPS1004K)	3m 29s
cross_build (mips64el, mips64el-linux-gnuabi64, DYNAMIC_ARCH=1 TARGET=GENERIC)	3m 57s
build (ubuntu-latest, gfortran, cmake)	44m 39s
build (macos-latest, gfortran, make)	10m 37s
build (macos-latest, gfortran, cmake)	11m 24s
cross_build (alpha, alpha-linux-gnu, TARGET=EV4)	2m 40s
build (ubuntu-latest, flang, cmake)	43m 25s
	4h 21m 47s

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