Don't check for popcount, clz, ctz or __builtin_constant_p

flint_clz and flint_ctz will be set during configuration based on which
longlong file to use. __builtin_constant_p will be defined only if
__GNUC__ is defined.

CMakeLists.txt

@@ -175,15 +175,6 @@ check_c_compiler_flag("-funroll-loops" HAS_FLAG_UNROLL_LOOPS)
 if(HAS_FLAG_MPOPCNT)
   set(CMAKE_REQUIRED_FLAGS "-mpopcnt")
 endif()
-# Testing __builtin_popcountl...
-check_c_source_runs([[int main(int argc, char ** argv) {
-  #if defined(_WIN64)
-  return __builtin_popcountll(argc) == 100;
-  #else
-  return __builtin_popcountl(argc) == 100;
-  #endif
-  }]] FLINT_USES_POPCNT)
-unset(CMAKE_REQUIRED_FLAGS)
 
 # fenv configuration
 check_c_source_compiles([[#include <fenv.h>

configure.ac

@@ -848,40 +848,6 @@ AC_MSG_ERROR([Couldn't find alloca, which is required for FLINT. Please submit a
 report to <https://github.com/flintlib/flint/issues/> and specify your
 operating system.])])
 
-AC_MSG_CHECKING([if $CC has CLZ intrinsics])
-AC_COMPILE_IFELSE(
-    [AC_LANG_PROGRAM([],[long int x = __builtin_clzl(3);])],
-    [AC_COMPILE_IFELSE(
-        [AC_LANG_PROGRAM([],[long long int x = __builtin_clzll(3);])],
-        [AC_MSG_RESULT([yes])
-         has_clz="yes"
-         AC_DEFINE(FLINT_HAS_CLZ,1,[Define if compiler has CLZ intrinsics])],
-        [AC_MSG_RESULT([no])]
-    )],
-    [AC_MSG_RESULT([no])]
-)
-
-AC_MSG_CHECKING([if $CC has CTZ intrinsics])
-AC_COMPILE_IFELSE(
-    [AC_LANG_PROGRAM([],[long int x = __builtin_ctzl(3);])],
-    [AC_COMPILE_IFELSE(
-        [AC_LANG_PROGRAM([],[long long int x = __builtin_ctzll(3);])],
-        [AC_MSG_RESULT([yes])
-         has_ctz="yes"
-         AC_DEFINE(FLINT_HAS_CTZ,1,[Define if compiler has CTZ intrinsics])],
-        [AC_MSG_RESULT([no])]
-    )],
-    [AC_MSG_RESULT([no])]
-)
-
-AC_MSG_CHECKING([if $CC has __builtin_constant_p])
-AC_COMPILE_IFELSE(
-    [AC_LANG_PROGRAM([], [int a = __builtin_constant_p(0 == 1);])],
-    [AC_MSG_RESULT([yes])
-     AC_DEFINE(FLINT_HAVE_CONSTANT_P,1,[Define if compiler has __builtin_constant_p])],
-    [AC_MSG_RESULT([no])]
-)
-
 ################################################################################
 # CFLAGS
 ################################################################################