Revert WARS related to __truncxfhf2

Bug: http://b/26165616
Bug: http://b/23535482

Revert "Add __truncxfhf2() to libclcore_g.bc as well on x86 targets."

This reverts commit 53f2796ad6c7487c298b49b62a0ea36ac95c54e5.

Revert "Implement __truncxfhf2 in driver/runtime"

This reverts commit d68b3c3a1ffa365e6be78afe74b3bf02bae3834d.
diff --git a/driver/runtime/Android.mk b/driver/runtime/Android.mk
index 9720f06..8db4394 100755
--- a/driver/runtime/Android.mk
+++ b/driver/runtime/Android.mk
@@ -69,8 +69,7 @@
     $(clcore_base_files) \
     arch/generic.c \
     arch/x86_sse2.ll \
-    arch/x86_sse3.ll \
-    arch/x86_trunc.ll
+    arch/x86_sse3.ll
 
 # Grab the current value for $(RS_VERSION_DEFINE)
 include frameworks/compile/slang/rs_version.mk
@@ -151,7 +150,6 @@
 LOCAL_CFLAGS += $(clcore_cflags)
 LOCAL_CFLAGS += -g -O0
 LOCAL_SRC_FILES := $(clcore_base_files) $(clcore_g_files)
-LOCAL_SRC_FILES_x86 := arch/x86_trunc.ll
 LOCAL_SRC_FILES_32 := arch/generic.c
 
 ifeq ($(TARGET_ARCH),$(filter $(TARGET_ARCH),arm64))
diff --git a/driver/runtime/arch/x86_trunc.ll b/driver/runtime/arch/x86_trunc.ll
deleted file mode 100644
index f8c1060..0000000
--- a/driver/runtime/arch/x86_trunc.ll
+++ /dev/null
@@ -1,11 +0,0 @@
-target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:32:32-n8:16:32-S128"
-target triple = "i686-unknown-linux"
-
-; http://b/26165616 - As a WAR for this bug, define __truncxfhf2.  Note that
-; this exhibits the double-rounding problem.  This WAR will be removed once
-; a proper implementation is added to compiler-rt.
-define half @__truncxfhf2(x86_fp80 %v1) nounwind readnone alwaysinline {
-  %1 = fptrunc x86_fp80 %v1 to float
-  %2 = fptrunc float %1 to half
-  ret half %2
-}