Fix Makefile typo

[nojb]

Following #10169 (I think)

[nojb]

Sorry, this is the wrong fix. By the way I am trying to fix the following warnings (observed in OS X and also in the RISC-V CI at least):

+ make -j4 --warn-undefined-variables
stdlib/StdlibModules:56: warning: undefined variable ' '
stdlib/StdlibModules:56: warning: undefined variable ' '
stdlib/StdlibModules:56: warning: undefined variable ' '
stdlib/StdlibModules:56: warning: undefined variable ' '
stdlib/StdlibModules:56: warning: undefined variable ' '
stdlib/StdlibModules:56: warning: undefined variable ' '
stdlib/StdlibModules:56: warning: undefined variable ' '
stdlib/StdlibModules:56: warning: undefined variable ' '
stdlib/StdlibModules:56: warning: undefined variable ' '
stdlib/StdlibModules:56: warning: undefined variable ' '
stdlib/StdlibModules:56: warning: undefined variable ' '
stdlib/StdlibModules:56: warning: undefined variable ' '
stdlib/StdlibModules:56: warning: undefined variable ' '
stdlib/StdlibModules:56: warning: undefined variable ' '
stdlib/StdlibModules:56: warning: undefined variable ' '
stdlib/StdlibModules:56: warning: undefined variable ' '
...

[Octachron]

My solution to please both check-typo and the undefined Makefile variable warning was to define a separate upper function:
https://github.com/ocaml/ocaml/blob/trunk/api_docgen/Makefile.docfiles#L22

[dra27]

A variant of this works:

--- a/stdlib/StdlibModules
+++ b/stdlib/StdlibModules
@@ -47,6 +47,9 @@ STDLIB_PREFIXED_MODULES=\

 # add stdlib__ as prefix to a module except for internal modules
 # and the stdlib module itself
+EMPTY=
+SPACE=$(EMPTY) $(EMPTY)
+$(SPACE) :=
 define add_stdlib_prefix
   $(or $(filter-out $(STDLIB_PREFIXED_MODULES), $1), \
     stdlib__$(shell echo $1 | cut -c1 | tr '[:lower:]' '[:upper:]')$\

More shortly...

[shindere]

I think the `EMPTY` variable is already defined in the build system so it may not be necessary to define it again here. Perhaps the SPACE variable can also be defined globally if used in more than one place.

[dra27]

Ack - just testing an alternate fix

[nojb]

Closing this in favor of #10270