ggc: Reduce GGC_QUIRE_SIZE on Solaris/SPARC [PR115031]

ggc: Reduce GGC_QUIRE_SIZE on Solaris/SPARC [PR115031]

g++.dg/modules/pr99023_b.X currently FAILs on 32-bit Solaris/SPARC:

FAIL: g++.dg/modules/pr99023_b.X -std=c++2a  1 blank line(s) in output
FAIL: g++.dg/modules/pr99023_b.X -std=c++2a (test for excess errors)

Excess errors:
cc1plus: out of memory allocating 1048344 bytes after a total of 7913472 bytes

It turns out that this exhaustion of the 32-bit address space happens
due to a combination of three issues:

* the SPARC pagesize of 8 kB,

* ggc-page.cc's chunk size of 512 * pagesize, i.e. 4 MB, and

* mmap adding two 8 kB unmapped red-zone pages to each mapping

which result in the 4 MB mappings to actually consume 4.5 MB of address
space.

To avoid this, this patch reduces the chunk size so it remains at 4 MB
even when combined with the red-zone pages, as recommended by mmap(2).

Tested on sparc-sun-solaris2.11 and sparcv9-sun-solaris2.11.

2024-05-29  Rainer Orth  <ro@CeBiTec.Uni-Bielefeld.DE>

	gcc:
	PR c++/115031
	* config/sparc/sol2.h (GGC_QUIRE_SIZE): Define as 510.