gcc: Disable use of sdt.h header

[Richard Purdie <richard.purdie@linuxfoundation.org>]

The target sysroot might contain sdt.h but we don't list this in DEPENDS
and shouldn't be referencing it. Unfortunately there is no way to tell
configure this since these tests are uncached and we can't force
a particular value. The only option is therefore to patch this out.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
---
diff --git a/meta/recipes-devtools/gcc/gcc-4.7.inc b/meta/recipes-devtools/gcc/gcc-4.7.inc
index 4905155..4ad4819 100644
--- a/meta/recipes-devtools/gcc/gcc-4.7.inc
+++ b/meta/recipes-devtools/gcc/gcc-4.7.inc
@@ -74,6 +74,7 @@ SRC_URI = "git://github.com/mirrors/gcc.git;branch=${BRANCH};protocol=git \
 	   file://arm-hard-float-loader.patch \
 	   file://gcc-argument-list-too-long.patch \
 	   file://fix-g++-sysroot.patch \
+	   file://disablesdt.patch \
 	  "
 
 S = "${TMPDIR}/work-shared/gcc-${PV}-${PR}/git"
diff --git a/meta/recipes-devtools/gcc/gcc-4.7/disablesdt.patch b/meta/recipes-devtools/gcc/gcc-4.7/disablesdt.patch
new file mode 100644
index 0000000..8946afc
--- /dev/null
+++ b/meta/recipes-devtools/gcc/gcc-4.7/disablesdt.patch
@@ -0,0 +1,32 @@
+We don't list dtrace in DEPENDS so we shouldn't be depending on this header. 
+It may or may not exist from preivous builds though. To be determinstic, disable
+sdt.h usage always. This avoids build failures if the header is removed after configure
+but before libgcc is compiled for example.
+
+RP 2012/8/7
+
+Upstream-Status: Inappropriate [hack]
+
+Index: git/gcc/configure
+===================================================================
+--- git.orig/gcc/configure	2012-08-07 21:18:42.319247701 +0000
++++ git/gcc/configure	2012-08-07 21:19:08.939247082 +0000
+@@ -26758,12 +26758,12 @@
+ { $as_echo "$as_me:${as_lineno-$LINENO}: checking sys/sdt.h in the target C library" >&5
+ $as_echo_n "checking sys/sdt.h in the target C library... " >&6; }
+ have_sys_sdt_h=no
+-if test -f $target_header_dir/sys/sdt.h; then
+-  have_sys_sdt_h=yes
+-
+-$as_echo "#define HAVE_SYS_SDT_H 1" >>confdefs.h
+-
+-fi
++#if test -f $target_header_dir/sys/sdt.h; then
++#  have_sys_sdt_h=yes
++#
++#$as_echo "#define HAVE_SYS_SDT_H 1" >>confdefs.h
++#
++#fi
+ { $as_echo "$as_me:${as_lineno-$LINENO}: result: $have_sys_sdt_h" >&5
+ $as_echo "$have_sys_sdt_h" >&6; }
+