The problem is that my Pentium G4500 does not support AVX instruction set extensions.
The GMP mathematical package is a requirement for compiling the GCC compiler. GMP configure reads the bios and upon finding a skylake family CPU assumes that it supports AVX. The system happily completes make and make install, but the binaries produced fail testing for "illegal instruction" (the missing AVX instructions).
The GCC compiler produced using these defective GMP libraries is subtly crippled. It happily compiles a defective operating system.
Could this problem be prevented by bios correctly informing the system of what instruction sets are supported?
ASRock B150M-ITX motherboard.
You can get processor specifications here: Intel® Pentium® Processor G4500 (3M Cache, 3.50 GHz) Specifications
Additional information with the product datasheet.