autotools: Replace the last few AC_HELP_STRING usages

AC_HELP_STRING is obsolete for a while, and AS_HELP_STRING is a drop-in
replacement we already use for the most part.

Author: b4n

build/geany.m4

@@ -2,7 +2,7 @@ AC_DEFUN([_GP_GEANY_LIBDIR],
 [
     AC_REQUIRE([PKG_PROG_PKG_CONFIG])
     AC_ARG_WITH([geany-libdir],
-        AC_HELP_STRING([--with-geany-libdir=PATH],
+        AS_HELP_STRING([--with-geany-libdir=PATH],
             [Set Geany's installation libdir [[default=auto]]]),
         [geany_libdir=${withval}],
         [geany_libdir=$(${PKG_CONFIG} --variable=libdir geany)])

build/geanylua.m4

@@ -3,7 +3,7 @@ AC_DEFUN([GP_CHECK_GEANYLUA],
     GP_ARG_DISABLE([GeanyLua], [auto])
 
     AC_ARG_WITH([lua-pkg],
-        AC_HELP_STRING([--with-lua-pkg=ARG],
+        AS_HELP_STRING([--with-lua-pkg=ARG],
             [name of Lua pkg-config script [[default=lua5.1]]]),
         [LUA_PKG_NAME=${withval%.pc}],
         [LUA_PKG_NAME=lua5.1

build/geanyvc.m4

@@ -3,7 +3,7 @@ AC_DEFUN([GP_CHECK_GEANYVC],
     GP_ARG_DISABLE([GeanyVC], [auto])
     GP_COMMIT_PLUGIN_STATUS([GeanyVC])
     AC_ARG_ENABLE(gtkspell,
-        AC_HELP_STRING([--enable-gtkspell=ARG],
+        AS_HELP_STRING([--enable-gtkspell=ARG],
             [Enable GtkSpell support in GeanyVC. [[default=auto]]]),,
         enable_gtkspell=auto)
     GP_CHECK_GTK3([gtkspell_package=gtkspell3-3.0],

build/lsp.m4

@@ -8,7 +8,7 @@ AC_DEFUN([GP_CHECK_LSP],
     JSONRPC_GLIB_VERSION=3.44
 
     AC_ARG_ENABLE(system-jsonrpc,
-        AC_HELP_STRING([--enable-system-jsonrpc],
+        AS_HELP_STRING([--enable-system-jsonrpc],
             [Force using system json-glib and jsonrpc-glib libraries for the LSP plugin. [[default=no]]]),,
         enable_system_jsonrpc=no)