configure: drop support for complex functions

They are not used since 520a5d33f0ea9f8838dbc7282470db700d248065.

configure

@@ -1317,21 +1317,6 @@ int main(void){ $func(); }
 EOF
 }
 
-check_complexfunc(){
-    log check_complexfunc "$@"
-    func=$1
-    narg=$2
-    shift 2
-    test $narg = 2 && args="f, g" || args="f * I"
-    disable $func
-    test_ld "cc" "$@" <<EOF && enable $func
-#include <complex.h>
-#include <math.h>
-float foo(complex float f, complex float g) { return $func($args); }
-int main(void){ return (int) foo; }
-EOF
-}
-
 check_mathfunc(){
     log check_mathfunc "$@"
     func=$1
@@ -2225,11 +2210,6 @@ INTRINSICS_LIST="
     intrinsics_neon
 "
 
-COMPLEX_FUNCS="
-    cabs
-    cexp
-"
-
 MATH_FUNCS="
     atanf
     atan2f
@@ -2404,7 +2384,6 @@ HAVE_LIST="
     $(add_suffix _inline   $ARCH_EXT_LIST)
     $ARCH_FEATURES
     $BUILTIN_LIST
-    $COMPLEX_FUNCS
     $HAVE_LIST_CMDLINE
     $HAVE_LIST_PUB
     $HEADERS_LIST
@@ -6545,10 +6524,6 @@ for func in $MATH_FUNCS; do
     eval check_mathfunc $func \${${func}_args:-1} $libm_extralibs
 done
 
-for func in $COMPLEX_FUNCS; do
-    eval check_complexfunc $func \${${func}_args:-1}
-done
-
 # these are off by default, so fail if requested and not available
 enabled avisynth          && { require_headers "avisynth/avisynth_c.h avisynth/avs/version.h" &&
                                { test_cpp_condition avisynth/avs/version.h "AVS_MAJOR_VER >= 3 && AVS_MINOR_VER >= 7 && AVS_BUGFIX_VER >= 1 || AVS_MAJOR_VER >= 3 && AVS_MINOR_VER > 7 || AVS_MAJOR_VER > 3" ||