howto configure so that CFLAGS='-g3 -O0' in gcc/Makefile?

[Larry Evans <cppljevans at suddenlink dot net>]

I'm trying to debug the compiler.  I've gotten the gcc/Makefile to
compile the programs with '-g3 -O0' so that no function called are
rm'ed (the -O0 option) and so that I can see what macros to (the -g3
option). However, I had to trial-and-error edit the Makefile's to
change what I thought was the macros for compile options to do it.  I
made several wrong guesses and had to make a different guess.  I
finally got it to work; however, then I had a problem with generating
the docs because the compile said I didn't have 'makeinfo'.  Well,
after installing makeinfo, I tried again with the same result.  So, I
reconfigured with ../src/configure <options>; however, that erased all
the changes I made to get '-g3 -O0' into the compile options.

So... I read `man gcc` which claimed passing "CFLAGS=<options>" on the
command line is how to do this.  Well, since <options> in my case was
'-g3 -O0' I had to pass it as CFLAGS='-g3 oO0'.  IOW:

  ../src/configure CFLAGS='-g3 -O0'

However, even then, it didn't work for the gcc/Makefile.  The top
level Makefile did have:

  TOPLEVEL_CONFIGURE_ARGUMENTS=../src/configure CFLAGS='-g3 -O0'
  ...
  CFLAGS_FOR_BUILD = -g3 -O0

However, the gcc/Makefile had:

  CFLAGS = -g3

so, it looks like passing the CFLAGS to the submake truncated the
option after the first word.  How do I avoid that?

TIA.

-Larry