Thank you, Jan-Henrik.
I forked the latest master and it appears that it does not build, unlike the 5.8.1 distribution load that is delivered in a tgz file. I did bootstrap the freshly checked out code with two minor warnings about "underquoted definition of AM_PATH_GTK". Then, I ran the "configure" script, which finished with no warnings or errors. Then, when I ran make, it failed in the bison-generated code, I believe. See the build log below. Is it a known issue?
$ ./configure --prefix=/home/smaslyak/tmp/monit-fix-bin --without-pam --without-ssl --enable-optimized --without-largefiles
...
$ make -j4
/sea/local/bin/flex -i -osrc/lex.yy.c src/l.l
bison -y -dvt -o src/y.tab.c src/p.y
bison -y -dvt -o src/y.tab.c src/p.y
echo "#include <config.h>" > src/.y.tab.c
echo "#include <config.h>" > src/.y.tab.c
cat src/y.tab.c >> src/.y.tab.c
cat src/y.tab.c >> src/.y.tab.c
mv src/.y.tab.c src/y.tab.c
mv src/.y.tab.c src/y.tab.c
mv src/y.tab.h src/tokens.h
mv: cannot stat `src/.y.tab.c': No such file or directory
make: [src/y.tab.c] Error 1 (ignored)
mv src/y.tab.h src/tokens.h
mv: cannot stat `src/y.tab.h': No such file or directory
make: [src/y.tab.c] Error 1 (ignored)
...
...
gcc -DHAVE_CONFIG_H -I. -I./src -DLINUX -DSYSCONFDIR="\"/home/smaslyak/tmp/monit-fix-bin/etc\"" -I./src -I./src/device -I./src/http -I./src/process -I./src/protocols -I./libmonit/src -Wno-pointer-sign -O2 -O3 -Wall -Wunused -Wno-unused-label -funsigned-char -D_GNU_SOURCE -std=c99 -D _REENTRANT -c -o src/monit.o src/monit.c
src/p.y:126: error: redefinition of 'struct IHavePrecedence'
src/p.y:132: error: redefinition of 'struct myrate'
src/p.y:155: error: redefinition of 'cfg_errflag'
src/p.y:155: error: previous definition of 'cfg_errflag' was here
src/p.y:156: error: redefinition of 'tail'
src/p.y:156: error: previous definition of 'tail' was here
src/p.y:157: error: redefinition of 'current'
src/p.y:157: error: previous definition of 'current' was here
src/p.y:158: error: redefinition of 'urlrequest'
src/p.y:158: error: previous definition of 'urlrequest' was here
...
...