Rechecked with GMP: if those options are not explicit specified GMP 6.1.2 automatically enables static library, disables shared.
GMP also gives a summary of the build options, both parts look reasonable to me so I suggest to do the same.
configure: summary of build options:
Version: GNU MP 6.1.2
Host type: i686-pc-mingw32
ABI: 32
Install prefix: /usr/local
Compiler: occ --nologo
Static libraries: yes
Shared libraries: no
Rechecked with GMP: if those options are not explicit specified GMP 6.1.2 automatically enables static library, disables shared. GMP also gives a summary of the build options, both parts look reasonable to me so I suggest to do the same.