Change in core[master]: restore --enable-symbols option again -- was FYI: Cleanup of debug options

[bringing the discussion to ML as it related to other thread on this topic]

Quoting "Lubos Lunák (via Code Review)" <gerrit@gerrit.libreoffice.org>:

> Lubos Lunák has posted comments on this change.
>
> Change subject: restore --enable-symbols option again
> ......................................................................
>
> Patch Set 2: Do not submit
>
> (2 inline comments)
>
> With this patch there would be two independent ways to control  
> whether -g is used, the other being ENABLE_DEBUGINFO_FOR, and  
> moreover this breaks the other way, i.e. the selective debuginfo  
> feature.
It seems to be not so easy to differentiate between two approaches:
* --enable-debug => which can be enhanced with selective debuginfo
* --enable-symbols (or whatever new name we want to give to that old option)

one option modifies optimization, another not
one option has impact on stl library, another not
one option can be extended with selective debuginfo, another not
[...]

So in this patch i started an attempt to follow the KISS principle and
make these approaches mutually exclusive: in the end it shouldn't be possible
to provide --enable-debug and --enable-symbols at once.
The result: one approach can not break another any more because they  
can not be
provided simultaneously.

> It also might be a good idea to reconsider the "symbols" name,  
> unless you want to repeatedly explain it to people who for some  
> reason keep getting confused by all this stuff over and over again  
> (it's a lot of fun I can assure you, and "debug" vs "debug symbols"  
> is just asking for it).
will do. Do you have any preferences?
--with-profile-info
--with-backtrace-info

> It possibly might make sense to fold --enable-symbols and  
> --enable-selective-debuginfo in one option and functionality.
Let us divide it in two different use cases to minimize the hassle here.

> Finally, I suggest the commit message just says that the option is  
> back in order to avoid having to specify -g or similar manually,  
> instead of the long list of claims you copied from the ML, as a  
> number of those claims are questionable or just plain incorrect.
will do.

> ....................................................
> File configure.ac
> Line 3374:         AC_MSG_ERROR([--enable-debug cannot be used with  
> --enable-symbols-only])
> Wrong option name (2x).
will do.

> ....................................................
> File solenv/gbuild/gbuild.mk
> Line 134: gb_SYMBOL := $(true)
> This makes --enable-debug/dbgutil and --enable-symbols dependant,
> even though your configure checks say that should not be used together.
yes, these options are mutually exclusive.

> Or, put differently, this breaks the selective debuginfo functionality.
Why? gb_SYMBOL is used only in --enable-symbols case.
My intention was not to touch --enable-debug/dbgutil case at all.

Regards
David