Fix typo in section list

[mhightower83]

For GCC LD scripts, using commas in a section expression sometimes cause problems.

With this change, .text.gdbstub* moved from IROM to IRAM where it was intended to be.
@earlephilhower please correct me or confirm. Thanks!

Resolves issue #8716

I could not find an explanation of how a "," was to be interpreted. It looks like a simple *(.somthing*, .something2*) worked; however, a more complex *(.text.something*, .text.something2*) did not - most of the time.

I don't have much experience with LD scripts. Anyone with more insight please help.

[earlephilhower]

From https://ftp.gnu.org/old-gnu/Manuals/ld-2.9.1/html_chapter/ld_3.html it looks like the comma should work, but it's also legal to just use spaces.

* (section)
* (section, section, ...)
* (section section ...)
    Instead of explicitly naming particular input files in a link control script, you can refer to all files from the ld command line: use `*' instead of a particular file name before the parenthesized input-file section list. If you have already explicitly included some files by name, `*' refers to all remaining files--those whose places in the output file have not yet been defined. For example, to copy sections 1 through 4 from an Oasys file into the .text section of an a.out file, and sections 13 and 14 into the .data section:

    SECTIONS {
      .text :{
        *("1" "2" "3" "4")
      }
      
      .data :{
        *("13" "14")
      }
    }

    `[ section ... ]' used to be accepted as an alternate way to specify named sections from all unallocated input files. Because some operating systems (VMS) allow brackets in file names, that notation is no longer supported. 

So, LGTM, especially since this was proven as fixing something broken!