This quadigraph used before a C preprocessor 'define' directive could be fooling M4, when processing this file, and make it think that the line contains a pure M4 'define' macro.
definition which might be defined in config.h or config-*.h files
needed, and being able to define it if appropriate for further configure tests as well as for the generated config file.
needed, and being able to define it if appropriate for further configure tests as well as for the generated config file. Introduced reentrant.m4 intended for our reentrant related autotools/m4 macros.