testsuite: xfail gcc.target/i386/pr91298-?.c on Solaris/x86 with as

The new gcc.target/i386/pr91298-?.c testcases FAIL on Solaris/x86 with the
native assembler:

FAIL: gcc.target/i386/pr91298-1.c (test for excess errors)

Excess errors:
Assembler: pr91298-1.c
        "/var/tmp//ccE6r3xb.s", line 5 : Syntax error
        Near line: "    .globl  $quux"
        "/var/tmp//ccE6r3xb.s", line 6 : Syntax error
        Near line: "    .type   $quux, @function"
        "/var/tmp//ccE6r3xb.s", line 7 : Syntax error
        Near line: "$quux:"
        "/var/tmp//ccE6r3xb.s", line 15 : Syntax error
        Near line: "    .size   $quux, .-$quux"
        "/var/tmp//ccE6r3xb.s", line 24 : Syntax error
        Near line: "    movl    $($a), %eax"
        "/var/tmp//ccE6r3xb.s", line 38 : Syntax error
        Near line: "    leal    ($a)(,%eax,4), %eax"
        "/var/tmp//ccE6r3xb.s", line 51 : Syntax error
        Near line: "    movl    ($a), %eax"
        "/var/tmp//ccE6r3xb.s", line 63 : Syntax error
        Near line: "    movl    ($a)+16, %eax"
        "/var/tmp//ccE6r3xb.s", line 97 : Syntax error
        Near line: "    movl    $($quux), %eax"
        "/var/tmp//ccE6r3xb.s", line 101 : Syntax error
        Near line: "    .globl  $a"
        "/var/tmp//ccE6r3xb.s", line 104 : Syntax error
        Near line: "    .type   $a, @object"
        "/var/tmp//ccE6r3xb.s", line 105 : Syntax error
        Near line: "    .size   $a, 72"
        "/var/tmp//ccE6r3xb.s", line 106 : Syntax error
        Near line: "$a:"
        "/var/tmp//ccE6r3xb.s", line 228 : Syntax error
        Near line: "    .long   ($a)"

FAIL: gcc.target/i386/pr91298-2.c (test for excess errors)

It only allows letters, digits, '_' and '.' in identifiers:
https://docs.oracle.com/cd/E37838_01/html/E61064/eqbsx.html#XALRMeoqjw

For lack of an effective-target keyword matching -fdollars-in-identifiers,
this patch fixes this by xfailing them on *-*-solaris2.* && !gas.

Tested on i386-pc-solaris2.11 with as and gas and x86_64-pc-linux-gnu.

	* gcc.target/i386/pr91298-1.c: xfail on Solaris/x86 with native
	assembler.
	* gcc.target/i386/pr91298-2.c: Likewise.