error: yacc.h: No such file or directory

Dear all,

I'm trying to run
sudo make buildworld
in a directory with r349168.

The result is:
cc  -O2 -pipe -I/usr/home/tuexen/head/usr.bin/mkesdb_static -I/usr/home/tuexen/head/usr.bin/mkesdb_static/../mkesdb  -I/usr/home/tuexen/head/usr.bin/mkesdb_static/../../lib/libc/iconv  -g -MD  -MF.depend.lex.o -MTlex.o -std=gnu99     -I/usr/obj/usr/home/tuexen/head/powerpc.powerpc64/tmp/legacy/usr/include -c lex.c -o lex.o
/usr/home/tuexen/head/usr.bin/mkesdb/lex.l:46:18: error: yacc.h: No such file or directory
/usr/home/tuexen/head/usr.bin/mkesdb/lex.l: In function 'yylex':
/usr/home/tuexen/head/usr.bin/mkesdb/lex.l:60: error: 'R_LN' undeclared (first use in this function)
/usr/home/tuexen/head/usr.bin/mkesdb/lex.l:60: error: (Each undeclared identifier is reported only once
/usr/home/tuexen/head/usr.bin/mkesdb/lex.l:60: error: for each function it appears in.)
/usr/home/tuexen/head/usr.bin/mkesdb/lex.l:72: error: 'yylval' undeclared (first use in this function)
/usr/home/tuexen/head/usr.bin/mkesdb/lex.l:73: error: 'L_IMM' undeclared (first use in this function)
/usr/home/tuexen/head/usr.bin/mkesdb/lex.l:76: error: 'R_NAME' undeclared (first use in this function)
/usr/home/tuexen/head/usr.bin/mkesdb/lex.l:77: error: 'R_ENCODING' undeclared (first use in this function)
/usr/home/tuexen/head/usr.bin/mkesdb/lex.l:78: error: 'R_VARIABLE' undeclared (first use in this function)
/usr/home/tuexen/head/usr.bin/mkesdb/lex.l:79: error: 'R_DEFCSID' undeclared (first use in this function)
/usr/home/tuexen/head/usr.bin/mkesdb/lex.l:80: error: 'R_INVALID' undeclared (first use in this function)
/usr/home/tuexen/head/usr.bin/mkesdb/lex.l:88: error: 'L_STRING' undeclared (first use in this function)
*** Error code 1

Stop.
make[3]: stopped in /usr/home/tuexen/head/usr.bin/mkesdb_static
*** Error code 1

Stop.
make[2]: stopped in /usr/home/tuexen/head
*** Error code 1

Stop.
make[1]: stopped in /usr/home/tuexen/head
*** Error code 1

Stop.
make: stopped in /usr/home/tuexen/head

This is on a 64 bit PPC system. Doing sudo rm -rf /usr/obj does not resolve the issue.

Any idea what is going wrong?

Best regards
Michael