build: support setting an emulator from configure script
V8’s JIT infrastructure requires binaries such as mksnapshot to be run during the build. However, these binaries must have the same bit-width as the host platform (e.g. a x86_64 build platform targeting ARMv6 needs to produce a 32-bit binary).
To work around this issue, allow building the binaries for the host platform and running them on the build platform with an emulator.
Based on Buildroot’s nodejs-src 0001-add-qemu-wrapper-support.patch. https://gitlab.com/buildroot.org/buildroot/-/blob/c1d5eada4d4db9eeaa1c44dd1dea95a67c8a70ca/package/nodejs/nodejs-src/0001-add-qemu-wrapper-support.patch