msabaoth.c: add alloca blurb to fix compilation on Solaris
msabaoth.c: add alloca blurb to fix compilation on Solaris

msabaoth.c:180: error: implicit declaration of function ?alloca?
http://monetdb.cwi.nl/testing/projects/monetdb/CurrentNew/logs/39194:176ae2b45904/GNU-Solaris-sparc/make.html#l758

zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb,zyzyis/monetdb