Adds Boost:MPI configuration check when enabled

The mpi.jam file is patched to enable the error

recipes/boost/all/conandata.yml

@@ -83,6 +83,8 @@ patches:
       base_path: "source_subfolder"
     - patch_file: "patches/boost_log_filesystem_no_deprecated_1_72.patch"
       base_path: "source_subfolder"
+    - patch_file: "patches/boost_mpi_check.patch"
+      base_path: "source_subfolder"
   1.73.0:
     - patch_file: "patches/boost_build_qcc_fix_debug_build_parameter.patch"
       base_path: "source_subfolder"

recipes/boost/all/patches/boost_mpi_check.patch

@@ -0,0 +1,24 @@
+diff -ru a/tools/build/src/tools/mpi.jam b/tools/build/src/tools/mpi.jam
+--- a/tools/build/src/tools/mpi.jam	2019-12-10 01:20:16.000000000 +0100
++++ b/tools/build/src/tools/mpi.jam	2020-09-02 13:17:22.942349254 +0200
+@@ -66,6 +66,8 @@
+ import type ;
+ import path ;
+
++import errors ;
++
+ # Make this module a project
+ project.initialize $(__name__) ;
+ project mpi ;
+@@ -539,6 +541,11 @@
+     # Set up the "mpi" alias
+     alias mpi : : : : $(options) ;
+   }
++
++  if ! $(.configured)
++  {
++	 errors.user-error "MPI not configured" ;
++  }     
+ }
+
+ # States whether MPI has bee configured