buildworld failing in lib/libc/db/btree

hi there,

for some reason buildworld always fails in lib/libc/db/btree :(

clang:

/usr/bin/clang -O2 -pipe -fno-strict-aliasing -fno-omit-frame-pointer -march=core2 -I/usr/git-freebsd-head/lib/libc/include -I/usr/git-freebsd-head/lib/libc/../../include -I/usr/git-freebsd-head/lib/libc/amd64 -DNLS  -D__DBINTERFACE_PRIVATE -I/usr/git-freebsd-head/lib/libc/.
/usr/git-freebsd-head/lib/libc/db/btree/bt_split.c:486:2: warning: implicit declaration of function '__PAST_END' is invalid in C99 [-Wimplicit-function-declaration]
        __PAST_END(h->linp, 1) = h->upper -= NRINTERNAL;
        ^
/usr/git-freebsd-head/lib/libc/db/btree/bt_split.c:486:25: error: expression is not assignable
        __PAST_END(h->linp, 1) = h->upper -= NRINTERNAL;
        ~~~~~~~~~~~~~~~~~~~~~~ ^
/usr/git-freebsd-head/lib/libc/db/btree/bt_split.c:538:26: error: expression is not assignable
                __PAST_END(h->linp, 1) = h->upper -= nbytes;
                ~~~~~~~~~~~~~~~~~~~~~~ ^
/usr/git-freebsd-head/lib/libc/db/btree/bt_split.c:554:26: error: expression is not assignable
                __PAST_END(h->linp, 1) = h->upper -= nbytes;
                ~~~~~~~~~~~~~~~~~~~~~~ ^
1 warning and 3 errors generated.
*** Error code 1

Stop in /usr/git-freebsd-head/lib/libc.
*** Error code 1

Stop in /usr/git-freebsd-head.
*** Error code 1

Stop in /usr/git-freebsd-head.
*** Error code 1

Stop in /usr/git-freebsd-head.
*** Error code 1

Stop in /usr/git-freebsd-head.

gcc:

/usr/bin/cc -O2 -pipe -fno-strict-aliasing -fno-omit-frame-pointer -frename-registers -march=core2 -I/usr/git-freebsd-head/lib/libc/include -I/usr/git-freebsd-head/lib/libc/../../include -I/usr/git-freebsd-head/lib/libc/amd64 -DNLS  -D__DBINTERFACE_PRIVATE -I/usr/git-freebsd
/usr/git-freebsd-head/lib/libc/db/btree/bt_split.c: In function 'bt_rroot':
/usr/git-freebsd-head/lib/libc/db/btree/bt_split.c:486: warning: implicit declaration of function '__PAST_END'
/usr/git-freebsd-head/lib/libc/db/btree/bt_split.c:486: error: lvalue required as left operand of assignment
/usr/git-freebsd-head/lib/libc/db/btree/bt_split.c: In function 'bt_broot':
/usr/git-freebsd-head/lib/libc/db/btree/bt_split.c:538: error: lvalue required as left operand of assignment
/usr/git-freebsd-head/lib/libc/db/btree/bt_split.c:554: error: lvalue required as left operand of assignment
*** Error code 1

Stop in /usr/git-freebsd-head/lib/libc.
*** Error code 1

Stop in /usr/git-freebsd-head.
*** Error code 1

Stop in /usr/git-freebsd-head.
*** Error code 1

Stop in /usr/git-freebsd-head.
*** Error code 1

Stop in /usr/git-freebsd-head.



...any recommendations how i can fix this? i'm tracking HEAD btw.

cheers.
alex