$ sudo libremakepkg -n parabola-i686

results in:

[...]
cc -MMD -MP -Wundef  -Wstrict-prototypes -Wmissing-prototypes -Wdisabled-optimization -Wno-pointer-sign -Wdeclaration-after-statement -std=gnu99  -D_POSIX_C_SOURCE=200112 -D_XOPEN_SOURCE=600 -D_ISOC99_SOURCE -I. -Iffmpeg -march=i686 -mtune=generic -O2 -pipe -fstack-protector-strong -fno-plt -g -fvar-tracking-assignments -fdebug-prefix-map=/build/mplayer/src=/usr/src/debug -fno-tree-vectorize -fno-asynchronous-unwind-tables -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE64_SOURCE -march=i686 -mtune=generic -O2 -pipe -fstack-protector-strong -fno-plt -g -fvar-tracking-assignments -fdebug-prefix-map=/build/mplayer/src=/usr/src/debug -D_FORTIFY_SOURCE=2 -DPIC -D_REENTRANT -I/usr/include/  -DZLIB_CONST -c -o stream/stream_smb.o stream/stream_smb.c
In file included from stream/stream_smb.c:21:
/usr/include/samba-4.0/libsmbclient.h:158:18: error: field 'btime_ts' has incomplete type
  struct timespec btime_ts;
                  ^~~~~~~~
/usr/include/samba-4.0/libsmbclient.h:162:18: error: field 'mtime_ts' has incomplete type
  struct timespec mtime_ts;
                  ^~~~~~~~
/usr/include/samba-4.0/libsmbclient.h:166:18: error: field 'atime_ts' has incomplete type
  struct timespec atime_ts;
                  ^~~~~~~~
/usr/include/samba-4.0/libsmbclient.h:170:18: error: field 'ctime_ts' has incomplete type
  struct timespec ctime_ts;
                  ^~~~~~~~
cc -MMD -MP -Wundef  -Wstrict-prototypes -Wmissing-prototypes -Wdisabled-optimization -Wno-pointer-sign -Wdeclaration-after-statement -std=gnu99  -D_POSIX_C_SOURCE=200112 -D_XOPEN_SOURCE=600 -D_ISOC99_SOURCE -I. -Iffmpeg -march=i686 -mtune=generic -O2 -pipe -fstack-protector-strong -fno-plt -g -fvar-tracking-assignments -fdebug-prefix-map=/build/mplayer/src=/usr/src/debug -fno-tree-vectorize -fno-asynchronous-unwind-tables -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -D_LARGEFILE64_SOURCE -march=i686 -mtune=generic -O2 -pipe -fstack-protector-strong -fno-plt -g -fvar-tracking-assignments -fdebug-prefix-map=/build/mplayer/src=/usr/src/debug -D_FORTIFY_SOURCE=2 -DPIC -D_REENTRANT -I/usr/include/  -DZLIB_CONST -c -o libmpcodecs/vd_theora.o libmpcodecs/vd_theora.c
make: *** [Makefile:726: stream/stream_smb.o] Error 1
make: *** Waiting for unfinished jobs....
==> ERROR: A failure occurred in build().
    Aborting...

The upstream¹ mplayer has the same versions and the same patches for x86_64. On i686, mplayer-glibc-2.27.patch was added on our side, but here it seem to fail because of samba.

[1]extra-x86_64 in git://git.archlinux.org/svntogit/packages.git

Denis.