Revert of Enable extended debugging symbols to including macro expansion. (https://codereview.chromium.org/198363002/)

Reason for revert:
Might be the cause for memory exhaustion during compilation on the Linux dbg build bot:

http://build.chromium.org/p/chromium.linux/buildstatus?builder=Linux%20Builder%20%28dbg%29%2832%29&number=21991

Original issue's description:
> Adding -g3 to get macro expansion support. (Default is -g2.)
> Adding -gdwarf-4 for macro expansion support.
> 
>  * gcc 4.6 outputs DWARF-2 by default
>  * gcc 4.7 outputs DWARF-4 by default
>  * clang <3.4 outputs DWARF-3 by default
>  * clang >3.4 outputs DWARF-4 by default
> 
> From http://gcc.gnu.org/onlinedocs/gcc/Debugging-Options.html
> > -g3
> >  Level 3 includes extra information, such as all the macro
> >  definitions present in the program. Some debuggers support macro
> >  expansion when you use -g3.
> >
> > -gdwarf-4
> >  Produce debugging information in DWARF format (if that is
> >  supported). The value of version may be either 2, 3 or 4; the
> >  default version for most targets is 4.  Note that with DWARF
> >  Version 2, some ports require and always use some non-conflicting
> >  DWARF 3 extensions in the unwind tables.
> >
> >  Version 4 may require GDB 7.0 and -fvar-tracking-assignments for
> >  maximum benefit.
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=257944

TBR=stuartmorgan@chromium.org,erg@chromium.org,mark@chromium.org,mmoss@chromium.org,thestig@chromium.org,mmoss@google.com,mithro@mithis.com
NOTREECHECKS=true
NOTRY=true

Review URL: https://codereview.chromium.org/203683007

git-svn-id: http://src.chromium.org/svn/trunk/src/build@257959 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

common.gypi

@@ -3077,14 +3077,9 @@
             ],
             'cflags': [
               '-O>(debug_optimize)',
-              '-gdwarf-4',
+              '-g',
             ],
             'conditions' : [
-              ['fastbuild==0', {
-                'cflags': [
-                  '-g3',
-                ],
-              }],
               ['OS=="android"', {
                 'ldflags': [
                   # Only link with needed input sections. This is to avoid