[As applied to 2.15]

commit 3857022a761ea7251f8e5c0e45d382ebc3e34cf9
Author: Ulrich Drepper <drepper@gmail.com>
Date:   Sun Jan 8 09:21:09 2012 -0500

     No need for test for __builtin_expect

diff -urpN glibc-2.15.orig/configure glibc-2.15/configure
--- glibc-2.15.orig/configure	2017-02-08 12:47:52.580858002 -0800
+++ glibc-2.15/configure	2017-02-08 13:01:40.682870318 -0800
@@ -7185,38 +7185,6 @@ if test "$libc_cv_c_asmcr0_bug" != 'no';
 fi
 fi
 
-{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for __builtin_expect" >&5
-$as_echo_n "checking for __builtin_expect... " >&6; }
-if ${libc_cv_gcc_builtin_expect+:} false; then :
-  $as_echo_n "(cached) " >&6
-else
-  cat > conftest.c <<EOF
-#line $LINENO "configure"
-int foo (int a)
-{
-  a = __builtin_expect (a, 10);
-  return a == 10 ? 0 : 1;
-}
-EOF
-if { ac_try='${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS -nostdlib -nostartfiles
-			    -o conftest conftest.c -lgcc >&5'
-  { { eval echo "\"\$as_me\":${as_lineno-$LINENO}: \"$ac_try\""; } >&5
-  (eval $ac_try) 2>&5
-  ac_status=$?
-  $as_echo "$as_me:${as_lineno-$LINENO}: \$? = $ac_status" >&5
-  test $ac_status = 0; }; }; then
-  libc_cv_gcc_builtin_expect=yes
-else
-  libc_cv_gcc_builtin_expect=no
-fi
-rm -f conftest*
-fi
-{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_gcc_builtin_expect" >&5
-$as_echo "$libc_cv_gcc_builtin_expect" >&6; }
-if test "$libc_cv_gcc_builtin_expect" = no; then
-  as_fn_error $? "support for __builtin_expect needed" "$LINENO" 5
-fi
-
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for __builtin_memset" >&5
 $as_echo_n "checking for __builtin_memset... " >&6; }
 if ${libc_cv_gcc_builtin_memset+:} false; then :
diff -urpN glibc-2.15.orig/configure.in glibc-2.15/configure.in
--- glibc-2.15.orig/configure.in	2017-02-08 12:47:52.580858002 -0800
+++ glibc-2.15/configure.in	2017-02-08 13:01:17.638580410 -0800
@@ -2098,28 +2098,6 @@ if test "$libc_cv_c_asmcr0_bug" != 'no';
 fi
 fi
 
-dnl Check whether compiler understands __builtin_expect.
-AC_CACHE_CHECK(for __builtin_expect, libc_cv_gcc_builtin_expect,
-[cat > conftest.c <<EOF
-#line $LINENO "configure"
-int foo (int a)
-{
-  a = __builtin_expect (a, 10);
-  return a == 10 ? 0 : 1;
-}
-EOF
-dnl No \ in command here because it ends up inside ''.
-if AC_TRY_COMMAND([${CC-cc} $CFLAGS $CPPFLAGS $LDFLAGS -nostdlib -nostartfiles
-			    -o conftest conftest.c -lgcc >&AS_MESSAGE_LOG_FD]); then
-  libc_cv_gcc_builtin_expect=yes
-else
-  libc_cv_gcc_builtin_expect=no
-fi
-rm -f conftest*])
-if test "$libc_cv_gcc_builtin_expect" = no; then
-  AC_MSG_ERROR([support for __builtin_expect needed])
-fi
-
 AC_CACHE_CHECK(for __builtin_memset, libc_cv_gcc_builtin_memset, [dnl
 cat > conftest.c <<\EOF
 void zero (void *x)