error: fix undeclared memcpy
error: fix undeclared memcpy

Some targets do not get string header file in, results in the warning:
implicit declaration of function 'memcpy'

mbedmicro/mbed,andcor02/mbed-os,andcor02/mbed-os,c1728p9/mbed-os,kjbracey-arm/mbed,kjbracey-arm/mbed,c1728p9/mbed-os,betzw/mbed-os,andcor02/mbed-os,mbedmicro/mbed,andcor02/mbed-os,c1728p9/mbed-os,mbedmicro/mbed,betzw/mbed-os,betzw/mbed-os,mbedmicro/mbed,kjbracey-arm/mbed,c1728p9/mbed-os,betzw/mbed-os,c1728p9/mbed-os,kjbracey-arm/mbed,betzw/mbed-os,andcor02/mbed-os,c1728p9/mbed-os,andcor02/mbed-os,betzw/mbed-os,mbedmicro/mbed