ocaml-mpi @1.01: fatal error: 'mpi.h' file not found

[ryandesign (Ryan Carsten Schmidt)]

ocaml-mpi isn't UsingTheRightCompiler or flags and doesn't build on any system:

​https://build.macports.org/builders/ports-14_x86_64-builder/builds/13272/steps/install-port/logs/stdio

gcc -I`ocamlc -where` -I/opt/local/include -O -g -Wall   -c -o init.o init.c
init.c:18:10: fatal error: 'mpi.h' file not found
#include <mpi.h>
         ^~~~~~~
1 error generated.