build: drop detecting gettimeofday() on Windows

To remove a build difference between mingw-w64 and MSVC builds (where
mingw-w64 has it, while MSVC does not). Also to simplify and save the
cost of detection/verification in CI.

`gettimeofday()` was used in `curl_threads.c` in codepath practically
unreachable in Windows builds, and in `tool_writeout.c` that falls back
to `time()` for targets without it.

Ref: #22593

Closes #22594

CMake/win32-cache.cmake

@@ -28,7 +28,6 @@ endif()
 if(MINGW)
   set(HAVE_BASENAME 1)
   set(HAVE_BOOL_T 1)  # = HAVE_STDBOOL_H
-  set(HAVE_GETTIMEOFDAY 1)
   set(HAVE_LIBGEN_H 1)
   set(HAVE_STDBOOL_H 1)
   set(HAVE_STDDEF_H 1)  # detected by CMake internally in check_type_size()
@@ -38,7 +37,6 @@ if(MINGW)
   set(HAVE_UNISTD_H 1)
   set(HAVE_UTIME_H 1)  # wrapper to sys/utime.h
 else()
-  set(HAVE_GETTIMEOFDAY 0)
   set(HAVE_LIBGEN_H 0)
   set(HAVE_STRINGS_H 0)
   set(HAVE_SYS_PARAM_H 0)

CMakeLists.txt

@@ -1647,7 +1647,6 @@ check_symbol_exists("fcntl"           "fcntl.h" HAVE_FCNTL)
 check_function_exists("getppid"       HAVE_GETPPID)
 check_function_exists("utimes"        HAVE_UTIMES)
 
-check_function_exists("gettimeofday"  HAVE_GETTIMEOFDAY)  # sys/time.h
 check_symbol_exists("closesocket"     "${CURL_INCLUDES}" HAVE_CLOSESOCKET)  # winsock2.h
 check_symbol_exists("sigsetjmp"       "setjmp.h" HAVE_SIGSETJMP)
 check_function_exists("getpass_r"     HAVE_GETPASS_R)
@@ -1688,6 +1687,7 @@ endif()
 if(NOT WIN32)
   check_include_file("dirent.h"         HAVE_DIRENT_H)
 
+  check_function_exists("gettimeofday"    HAVE_GETTIMEOFDAY)  # sys/time.h
   check_function_exists("if_nametoindex"  HAVE_IF_NAMETOINDEX)  # net/if.h
   check_function_exists("realpath"        HAVE_REALPATH)
   check_function_exists("sched_yield"     HAVE_SCHED_YIELD)

configure.ac

@@ -4226,7 +4226,6 @@ AC_CHECK_FUNCS([\
   getpwuid \
   getpwuid_r \
   getrlimit \
-  gettimeofday \
   mach_absolute_time \
   pipe \
   poll \
@@ -4249,6 +4248,7 @@ fi
 
 if test "$curl_cv_native_windows" != "yes"; then
   AC_CHECK_FUNCS([\
+    gettimeofday \
     if_nametoindex \
     realpath \
     sched_yield \