fix the autoconf script to correctly set CONFIGURE_ARGS (#3263)

fixed the autoconf script to correctly set CONFIGURE_ARGS

Author: jvanburen

configure.ac

@@ -23,6 +23,12 @@ AC_INIT([The Flambda backend for OCaml],
         [flambda_backend],
         [http://github.com/ocaml-flambda/flambda_backend])
 
+
+## Command-line arguments passed to configure
+# This must be set very soon after AC_INIT to avoid other macros from clobbering
+# argv
+CONFIGURE_ARGS="$*"
+
 DUNE_MAX_VERSION=[3.15]
 
 AC_MSG_NOTICE([Configuring Flambda backend version AC_PACKAGE_VERSION])
@@ -107,9 +113,6 @@ AC_SUBST([main_build_profile])
 
 # Configuration variables
 
-## Command-line arguments passed to configure
-CONFIGURE_ARGS="$*"
-
 # Command to build executables
 # Ultimately, MKEXE may build an executable using the C compiler or it may use
 # a wrapper for a linker (i.e. flexlink). The build system must therefore not