Changeset 51614c01 in rtems for c/src/lib/libbsp/i386

i386/smp: Have ld use incremental build for appstart.o

With HAS_SMP set, we have:

libbsp_a_LIBADD += appstart.$(OBJEXT)

When trying to build appstart.o, however, we link start.o with appcpustart.o
through the linkcmds script, which leaves several symbols unresolved, and
without the "-r" (or -i) flag, this throws undefined reference errors.

This change requires us to re-run the ./bootstrap script to regenerate
Makefile.in, and therefore the Makefile for the particular BSP as well.

Complete log of errors available here:
​https://gist.github.com/AmaanC/d40bd7393dca1f82965938275845b7f9

Updates #3331