undeclared var's in libmutt

[Timothy Flechtner <Timothy Flechtner tellabs com>]

olah amigos,
  i'm trying to compile 0.8.1 on an ultra 5, running solaris 2.6, and i
get the following bad news:

Making all in libmutt
make[2]: Entering directory
`/home/tellabd-4/tflecht/sw/balsa-0.8.1/libmutt'
gcc -DHAVE_CONFIG_H -I. -I. -I. -I. 
-DSHAREDIR=\"/home/tellabd-4/tflecht/usr/local/share\"
-DSYSCONFDIR=\"/home/tellabd-4/tflecht/usr/local/etc\" -DLIBMUTT  -g -O2
-c mx.c
mx.c: In function `mx_lock_file':
mx.c:199: `LOCK_EX' undeclared (first use in this function)
mx.c:199: (Each undeclared identifier is reported only once
mx.c:199: for each function it appears in.)
mx.c:199: `LOCK_SH' undeclared (first use in this function)
mx.c:199: `LOCK_NB' undeclared (first use in this function)
mx.c:246: `LOCK_UN' undeclared (first use in this function)
mx.c: In function `mx_unlock_file':
mx.c:267: `LOCK_UN' undeclared (first use in this function)
make[2]: *** [mx.o] Error 1
make[2]: Leaving directory
`/home/tellabd-4/tflecht/sw/balsa-0.8.1/libmutt'
make[1]: *** [all-recursive] Error 1
make[1]: Leaving directory `/home/tellabd-4/tflecht/sw/balsa-0.8.1'
make: *** [all-recursive-am] Error 2

i can't seem to find any definitions of these in any .h in /include,
/usr/include, or any place else.  can anyone tell me what i'm missing?

thanks!
-tim