[OE-core] syslinux + gcc 5.2 build error

[Andre McCurdy]

I'm seeing what looks like a gcc bug when building syslinux with
certain combinations of TUNE_CCARGS. A specific combination which
fails is:

  TUNE_CCARGS = " -m32 -march=core2 -mtune=core2 -msse3 -mfpmath=sse
-fschedule-insns"

( ie the default flags set by tune-core2.inc with one additional flag:
-fschedule-insns )

Problem is only seen with gcc 5.2

Compiler error is:

i686-rdk-linux-gcc -m32 -march=core2 -mtune=core2 -msse3 -mfpmath=sse
-fschedule-insns
--sysroot=/home/andre/rdk/rdk-master/build-vbox32/tmp/sysroots/vbox32
-O2 -pipe -g -feliminate-unused-debug-types -fstack-protector-strong
-D_FORTIFY_SOURCE=2 -MT zlib/deflate.o -MD -Os -march=i386
-falign-functions=0 -falign-jumps=0 -falign-labels=0 -ffast-math
-fomit-frame-pointer -std=gnu99 -m32 -mpreferred-stack-boundary=2
-fno-stack-protector -fwrapv -freg-struct-return -fPIC -fno-exceptions
-fno-asynchronous-unwind-tables -fno-strict-aliasing
-falign-functions=0 -falign-jumps=0 -falign-labels=0 -falign-loops=0
-g -D__COM32__ -D__FIRMWARE_BIOS__ -nostdinc -iwithprefix include -I.
-I/home/andre/rdk/rdk-master/build-vbox32/tmp/work/core2-32-rdk-linux/syslinux/6.03-r0/syslinux-6.03/com32/lib/sys
-I/home/andre/rdk/rdk-master/build-vbox32/tmp/work/core2-32-rdk-linux/syslinux/6.03-r0/syslinux-6.03/com32/lib/../include
-I/home/andre/rdk/rdk-master/build-vbox32/tmp/work/core2-32-rdk-linux/syslinux/6.03-r0/syslinux-6.03/com32/include/sys
-I/home/andre/rdk/rdk-master/build-vbox32/tmp/work/core2-32-rdk-linux/syslinux/6.03-r0/syslinux-6.03/core/include
-I/home/andre/rdk/rdk-master/build-vbox32/tmp/work/core2-32-rdk-linux/syslinux/6.03-r0/syslinux-6.03/com32/lib/
-I/home/andre/rdk/rdk-master/build-vbox32/tmp/work/core2-32-rdk-linux/syslinux/6.03-r0/syslinux-6.03/com32/lib/sys/module
-I/home/andre/rdk/rdk-master/build-vbox32/tmp/work/core2-32-rdk-linux/syslinux/6.03-r0/syslinux-6.03/bios/com32/lib//../..
-W -Wall -Wstrict-prototypes -Wpointer-arith -Wwrite-strings
-Wstrict-prototypes -Winline -DDYNAMIC_CRC_TABLE -DPNG_NO_CONSOLE_IO
-DPNG_NO_WRITE_SUPPORTED -DPNG_NO_MNG_FEATURES -DPNG_NO_READ_tIME
-DPNG_NO_WRITE_tIME -mregparm=3 -DREGPARM=3 -c -o zlib/deflate.o
/home/andre/rdk/rdk-master/build-vbox32/tmp/work/core2-32-rdk-linux/syslinux/6.03-r0/syslinux-6.03/com32/lib/zlib/deflate.c

/home/andre/rdk/rdk-master/build-vbox32/tmp/work/core2-32-rdk-linux/syslinux/6.03-r0/syslinux-6.03/com32/lib/zlib/deflate.c:
In function 'deflate':
/home/andre/rdk/rdk-master/build-vbox32/tmp/work/core2-32-rdk-linux/syslinux/6.03-r0/syslinux-6.03/com32/lib/zlib/deflate.c:892:1:
error: unable to find a register to spill
 }
 ^
/home/andre/rdk/rdk-master/build-vbox32/tmp/work/core2-32-rdk-linux/syslinux/6.03-r0/syslinux-6.03/com32/lib/zlib/deflate.c:892:1:
error: this is the insn:
(insn 745 1859 1860 94 (set (reg:QI 995)
        (mem/j:QI (plus:SI (reg/v/f:SI 965 [orig:676 strm ] [676])
                (const_int 48 [0x30])) [0 strm_54(D)->adler+0 S1
A32])) /home/andre/rdk/rdk-master/build-vbox32/tmp/work/core2-32-rdk-linux/syslinux/6.03-r0/syslinux-6.03/com32/lib/zlib/deflate.c:775
86 {*movqi_internal}
     (nil))
/home/andre/rdk/rdk-master/build-vbox32/tmp/work/core2-32-rdk-linux/syslinux/6.03-r0/syslinux-6.03/com32/lib/zlib/deflate.c:892:
confused by earlier errors, bailing out