Set carry flag before calling INT 15,e801 and INT 15,e820.

Ignore carry flag for INT 15,88; the Ralf Brown interrupt list says
that CF is unreliable for this call.

src/arch/i386/firmware/pcbios/memmap.c

 	unsigned int extmem;
 
 	REAL_EXEC ( rm_mem_e801,
+		    "stc\n\t"
 		    "int $0x15\n\t"
 		    "pushfw\n\t"
 		    "popw %w0\n\t",
 	uint16_t extmem;
 
 	REAL_EXEC ( rm_mem_88,
-		    "int $0x15\n\t"
-		    "jnc 1f\n\t"
-		    "xorw %%ax, %%ax\n\t"
-		    "\n1:\n\t",
+		    /* Ignore CF; it is not reliable for this call */
+		    "int $0x15\n\t",
 		    1,
 		    OUT_CONSTRAINTS ( "=a" ( extmem ) ),
 		    IN_CONSTRAINTS ( "a" ( 0x8800 ) ),
 
 	do {
 		REAL_EXEC ( rm_mem_e820,
+			    "stc\n\t"
 			    "int $0x15\n\t"
 			    "pushfw\n\t"
 			    "popw %w0\n\t",