configure: remove use of deprecated macros

AC_HEADER_TIME, AC_HEADER_STDC and AC_TYPE_SIGNAL

acinclude.m4

@@ -1408,7 +1408,6 @@ dnl -------------------------------------------------
 dnl Check for timeval struct
 
 AC_DEFUN([CURL_CHECK_STRUCT_TIMEVAL], [
-  AC_REQUIRE([AC_HEADER_TIME])dnl
   AC_REQUIRE([CURL_CHECK_HEADER_WINSOCK])dnl
   AC_REQUIRE([CURL_CHECK_HEADER_WINSOCK2])dnl
   AC_CHECK_HEADERS(sys/types.h sys/time.h time.h sys/socket.h)
@@ -1606,7 +1605,6 @@ dnl -------------------------------------------------
 dnl Check if monotonic clock_gettime is available.
 
 AC_DEFUN([CURL_CHECK_FUNC_CLOCK_GETTIME_MONOTONIC], [
-  AC_REQUIRE([AC_HEADER_TIME])dnl
   AC_CHECK_HEADERS(sys/types.h sys/time.h time.h)
   AC_MSG_CHECKING([for monotonic clock_gettime])
   #

configure.ac

@@ -4246,13 +4246,6 @@ case "$OPT_FISH_FPATH" in
     ;;
 esac
 
-dnl **********************************************************************
-dnl Back to "normal" configuring
-dnl **********************************************************************
-
-dnl Checks for header files.
-AC_HEADER_STDC
-
 CURL_CHECK_HEADER_MALLOC
 CURL_CHECK_HEADER_MEMORY
 
@@ -4338,7 +4331,7 @@ dnl Checks for typedefs, structures, and compiler characteristics.
 AC_C_CONST
 CURL_CHECK_VARIADIC_MACROS
 AC_TYPE_SIZE_T
-AC_HEADER_TIME
+
 CURL_CHECK_STRUCT_TIMEVAL
 CURL_VERIFY_RUNTIMELIBS
 
@@ -4453,8 +4446,6 @@ TYPE_SOCKADDR_STORAGE
 
 TYPE_SIG_ATOMIC_T
 
-AC_TYPE_SIGNAL
-
 CURL_CHECK_FUNC_SELECT
 
 CURL_CHECK_FUNC_RECV

m4/curl-functions.m4

@@ -446,7 +446,6 @@ dnl Set up variable with list of headers that must be
 dnl included when time.h is to be included.
 
 AC_DEFUN([CURL_INCLUDES_TIME], [
-AC_REQUIRE([AC_HEADER_TIME])dnl
 curl_includes_time="\
 /* includes start */
 #ifdef HAVE_SYS_TYPES_H