mulmod_shoup and nmod_vec_scalar_mul_nmod #2775

Job	Run time
macOS-x86 Clang with BLAS (x2)	18m 13s
macOS-M1, Clang (x3)	8m 50s
Alpine Linux, musl, 32-bit (assert, x1.5)	14m 2s
GCC build regression check (no tests)	1m 7s
MinGW GCC (x0.5)	10m 34s
MSVC (x1)	9m 46s
Nemo.jl (temporary branch)	11m 59s
Ubuntu Clang with examples (x5)	12m 56s
Ubuntu GCC, Code Coverage (x10)	29m 52s
Ubuntu GCC with NTL (assert, x2)	8m 30s
	2h 5m 49s

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