'make check' fails if there is a space in the filename

[Christopher Jefferson]

If I build gmp 6.1.0 in a directory containing a space, then make
check fails with:

/bin/sh ../libtool  --tag=CC   --mode=link gcc  -O2 -pedantic
-fomit-frame-pointer -m64 -mtune=haswell -march=haswell   -o t-bswap
t-bswap.o libtests.la ../libgmp.la
libtool:   error: cannot find the library 'stuff/gmp-6.1.0/libgmp.la'
or unhandled argument 'stuff/gmp-6.1.0/libgmp.la'

Looking inside tests/libtests.la, I see:

dependency_libs=' stuff/gmp-6.1.0/libgmp.la /Users/caj/temp/my'

Somehow, the filename has got messed up here (the directory should be
../my stuff/gmp-6.1.0/...)