[m-rev.] diff: Hide mercury_string_conversions.h from string.mh

[Peter Wang]

[I assume mercury_string_conversions.h wasn't intended to be installed.]

Hide mercury_string_conversions.h from string.mh

library/string.m:
    Include mercury_string_conversions.h header in a 'local'
    foreign_decl declaration to prevent the inclusion from appearing in
    the generated string.mh file. The new header file is not installed
    so including it from string.mh creates a broken installation.

diff --git a/library/string.m b/library/string.m
index d4b4292c16..35b54d2828 100644
--- a/library/string.m
+++ b/library/string.m
@@ -1961,7 +1961,9 @@
 
 #include ""mercury_string.h""   // for MR_allocate_aligned_string*() etc.
 #include ""mercury_tags.h""     // for MR_list_*()
+").
 
+:- pragma foreign_decl("C", local, "
 #include ""mercury_string_conversions.h""
 ").
 
-- 
2.54.0