ld: Set COMMONPAGESIZE for i386 Solaris

Since COMMONPAGESIZE is set for other Solaris targets, including x86-64
Solaris, also set COMMONPAGESIZE for i386 Solaris to fix

FAIL: Build pr20995-2.so
FAIL: pr20995-2

	PR 25732
	* emulparams/elf_i386_ldso.sh (COMMONPAGESIZE): New.
	* testsuite/ld-elf/shared.exp:Don't xfail pr20995-2 tests for
	Solaris.