pkg/48680: gcc48 chokes on ffmpeg2 inline assembly (i386-6.99.38)

[jdbaker%mylinuxisp.com@localhost]

>Number:         48680
>Category:       pkg
>Synopsis:       gcc48 chokes on ffmpeg2 inline assembly (i386-6.99.38)
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    pkg-manager
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Tue Mar 25 21:55:00 +0000 2014
>Originator:     John D. Baker
>Release:        NetBSD/i386-6.99.38(gcc48), pkgsrc-HEAD (pre-pkgsrc-2014Q1)
>Organization:
>Environment:
NetBSD gx260a 6.99.38 NetBSD 6.99.38 (GENERIC) #11: Mon Mar 24 22:17:52 CDT 
2014  
sysop%verthandi.technoskunk.fur@localhost:/d0/build/current/obj/i386/sys/arch/i386/compile/GENERIC
 i386

>Description:
On NetBSD/i386-6.99.38 built with HAVE_GCC=48 and thus using gcc 4.8.3, building
multimedia/ffmpeg2 fails as follows:

[...]
CC      libavcodec/x86/ac3dsp_init.o
libavcodec/x86/ac3dsp_init.c: In function 'ac3_downmix_sse':
libavcodec/x86/ac3dsp_init.c:65:5: error: 'asm' operand has impossible 
constraints
     __asm__ volatile (                                          \
     ^
libavcodec/x86/ac3dsp_init.c:149:9: note: in expansion of macro 'MIX5'
         MIX5(IF0, IF1);
         ^
libavcodec/x86/ac3dsp_init.c:65:5: error: 'asm' operand has impossible 
constraints
     __asm__ volatile (                                          \
     ^
libavcodec/x86/ac3dsp_init.c:153:9: note: in expansion of macro 'MIX5'
         MIX5(IF1, IF0);
         ^
common.mak:48: recipe for target 'libavcodec/x86/ac3dsp_init.o' failed
gmake: *** [libavcodec/x86/ac3dsp_init.o] Error 1
*** Error code 2

Stop.
make[1]: stopped in /x/pkgsrc/multimedia/ffmpeg2
[...]
>How-To-Repeat:
On a NetBSD/i386-current system using gcc 4.8.3 (amd64? other gcc48-ready 
arches?)
attempt to build multimedia/ffmpeg2
>Fix: