From command line:

--->  Attempting to fetch pixman-0.26.0.tar.bz2 from http://xorg.freedesktop.org/archive/individual/lib/
--->  Verifying checksum(s) for libpixman
--->  Extracting libpixman
--->  Configuring libpixman
--->  Building libpixman
Error: org.macports.build for port libpixman returned: command execution failed
Error: Failed to install libpixman
Please see the log file for port libpixman for details:
    /opt/local/var/macports/logs/_opt_local_var_macports_sources_rsync.macports.org_release_ports_graphics_libpixman/libpixman/main.log
Error: The following dependencies were not installed: gst-plugins-base gnome-vfs gconf gtk2 pango cairo libpixman xorg-xcb-util shared-mime-info xorg-libXcomposite xorg-compositeproto xorg-libXext xorg-xextproto xorg-libXfixes xorg-fixesproto xorg-libXcursor xorg-libXdamage xorg-damageproto xorg-libXi xorg-inputproto xorg-libXinerama xorg-xineramaproto xorg-libXrandr xorg-randrproto orbit2 libidl policykit eggdbus gnome-mime-data intltool p5.12-getopt-long perl5.12 gdbm p5.12-pathtools p5.12-scalar-list-utils p5.12-xml-parser gstreamer bison m4 flex libtheora libvorbis libogg orc lcms libxslt mesa makedepend py27-libxml2 xorg-dri2proto xorg-glproto xorg-libXmu xorg-libXt xorg-libsm xorg-libice xorg-libXxf86vm xorg-xf86vidmodeproto
To report a bug, follow the instructions in the guide:
    http://guide.macports.org/#project.tickets
Error: Processing of port wine failed

===============================================
From main.log:

:info:build /bin/sh ../libtool  --tag=CC   --mode=compile /usr/bin/clang -DHAVE_CONFIG_H -I. -I..   -I/opt/local/include  -msse2 -Winline -pipe -O2 -arch x86_64 -Wall -fno-strict-aliasing -fvisibility=hidden -c -o libpixman_sse2_la-pixman-sse2.lo `test -f 'pixman-sse2.c' || echo './'`pixman-sse2.c
:info:build libtool: compile:  /usr/bin/clang -DHAVE_CONFIG_H -I. -I.. -I/opt/local/include -msse2 -Winline -pipe -O2 -arch x86_64 -Wall -fno-strict-aliasing -fvisibility=hidden -c pixman-sse2.c  -fno-common -DPIC -o .libs/libpixman_sse2_la-pixman-sse2.o
:info:build fatal error: error in backend: Unsupported asm: input constraint with a matching output constraint of incompatible type!
:info:build make[3]: *** [libpixman_mmx_la-pixman-mmx.lo] Error 1
:info:build make[3]: *** Waiting for unfinished jobs....
:info:build libtool: compile:  /usr/bin/clang -DHAVE_CONFIG_H -I. -I.. -I/opt/local/include -msse2 -Winline -pipe -O2 -arch x86_64 -Wall -fno-strict-aliasing -fvisibility=hidden -c pixman-sse2.c -o libpixman_sse2_la-pixman-sse2.o >/dev/null 2>&1
:info:build make[3]: Leaving directory `/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_ports_graphics_libpixman/libpixman/work/pixman-0.26.0-x86_64/pixman'
:info:build make[2]: *** [all] Error 2
:info:build make[2]: Leaving directory `/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_ports_graphics_libpixman/libpixman/work/pixman-0.26.0-x86_64/pixman'
:info:build make[1]: *** [all-recursive] Error 1
:info:build make[1]: Leaving directory `/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_ports_graphics_libpixman/libpixman/work/pixman-0.26.0-x86_64'
:info:build make: *** [all] Error 2
:info:build make: Leaving directory `/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_ports_graphics_libpixman/libpixman/work/pixman-0.26.0-x86_64'
:info:build Command failed:  cd "/opt/local/var/macports/build/_opt_local_var_macports_sources_rsync.macports.org_release_ports_graphics_libpixman/libpixman/work/pixman-0.26.0-x86_64" && /usr/bin/make -j4 -w all V=1 
:info:build Exit code: 2
:error:build org.macports.build for port libpixman returned: command execution failed
:debug:build Error code: NONE
:debug:build Backtrace: command execution failed
    while executing
"$procedure $targetname"
:info:build Warning: targets not executed for libpixman: org.macports.activate org.macports.build org.macports.destroot org.macports.install
:error:build Failed to install libpixman