m4: grab newer upstream m4 (for code-coverage)

Grab some newer version of the autotools m4 archive, as we need those to
setup code-coverage.

Remove some unneeded ones.

m4/ax_compiler_flags_gir.m4

@@ -0,0 +1,60 @@
+# ===========================================================================
+#  https://www.gnu.org/software/autoconf-archive/ax_compiler_flags_gir.html
+# ===========================================================================
+#
+# SYNOPSIS
+#
+#   AX_COMPILER_FLAGS_GIR([VARIABLE], [IS-RELEASE], [EXTRA-BASE-FLAGS], [EXTRA-YES-FLAGS])
+#
+# DESCRIPTION
+#
+#   Add warning flags for the g-ir-scanner (from GObject Introspection) to
+#   VARIABLE, which defaults to WARN_SCANNERFLAGS.  VARIABLE is AC_SUBST-ed
+#   by this macro, but must be manually added to the SCANNERFLAGS variable
+#   for each GIR target in the code base.
+#
+#   This macro depends on the environment set up by AX_COMPILER_FLAGS.
+#   Specifically, it uses the value of $ax_enable_compile_warnings to decide
+#   which flags to enable.
+#
+# LICENSE
+#
+#   Copyright (c) 2015 Philip Withnall <philip@tecnocode.co.uk>
+#
+#   Copying and distribution of this file, with or without modification, are
+#   permitted in any medium without royalty provided the copyright notice
+#   and this notice are preserved.  This file is offered as-is, without any
+#   warranty.
+
+#serial 6
+
+AC_DEFUN([AX_COMPILER_FLAGS_GIR],[
+    AX_REQUIRE_DEFINED([AX_APPEND_FLAG])
+
+    # Variable names
+    m4_define([ax_warn_scannerflags_variable],
+              [m4_normalize(ifelse([$1],,[WARN_SCANNERFLAGS],[$1]))])
+
+    # Base flags
+    AX_APPEND_FLAG([$3],ax_warn_scannerflags_variable)
+
+    AS_IF([test "$ax_enable_compile_warnings" != "no"],[
+        # "yes" flags
+        AX_APPEND_FLAG([ dnl
+            --warn-all dnl
+            $4 dnl
+            $5 dnl
+            $6 dnl
+            $7 dnl
+        ],ax_warn_scannerflags_variable)
+    ])
+    AS_IF([test "$ax_enable_compile_warnings" = "error"],[
+        # "error" flags
+        AX_APPEND_FLAG([ dnl
+            --warn-error dnl
+        ],ax_warn_scannerflags_variable)
+    ])
+
+    # Substitute the variables
+    AC_SUBST(ax_warn_scannerflags_variable)
+])dnl AX_COMPILER_FLAGS