error: Fix support for library namespacing (regression 2023-05-27). * lib/error.in.h (error): If error is defined as a macro, define a static inline function _gl_inline_error that invokes it, and let the new error macro invoke that function. (error_at_line): If error_at_line is defined as a macro, define a static inline function _gl_inline_error_at_line that invokes it, and let the new error_at_line macro invoke that function.