scripts: LDSO is defined for CC and libc

the LDSO (/lib/ld.so.1) is generated with the libc. It's name must be the same with the LDSO path used during the link operation of any applications.
 - Makefile defines the name of LDSO
 - project.mk defines the LDFLAGS argument to use LDSO as linker
 - libc/Makefile specifies the name of the LDSO for the libc subproject (glibc and musl currently)
scripts: libgcc is required for any GCC build

GCC build binary with some codes available outside the binary. This code is stored inside libgcc. This library is shared or static but in each case the binary must be linked to libgcc.
at the run time, libgcc_h.so is required when you start an application build with GCC.
scripts: unverbose some file generators

some files is generated and it's command require $(Q) prefix to display or not the command. the V=1 option enable or disable $(Q)
bootloader: boot.scr rebuilds if necessary