[NaCl SDK] Enable linux host build for nacl_io and nacl_io_tests.

native_client_sdk/src/tools/nacl_gcc.mk

Index: native_client_sdk/src/tools/nacl_gcc.mk
diff --git a/native_client_sdk/src/tools/nacl_gcc.mk b/native_client_sdk/src/tools/nacl_gcc.mk
index 675b46451bb59f5a81db3b99ef05ccc295105398..2727447341df7555b0c5682b125829b8c06d19b2 100644
--- a/native_client_sdk/src/tools/nacl_gcc.mk
+++ b/native_client_sdk/src/tools/nacl_gcc.mk
@@ -452,3 +452,17 @@ GDB_DEBUG_TARGET = $(abspath $(OUTDIR))/$(TARGET)_$(SYSARCH).nexe
 else
 GDB_DEBUG_TARGET = $(abspath $(OUTDIR))/$(LIB_NAME)/runnable-ld.so
 endif
+
+ifdef STANDALONE
+run: all
+ifndef NACL_ARCH
+	$(error Cannot run in sel_ldr unless $$NACL_ARCH is set)
+endif
+	$(SEL_LDR_PATH) $(SEL_LDR_ARGS) $(OUTDIR)/$(TARGET)_$(NACL_ARCH).nexe -- $(EXE_ARGS)
+
+debug: all
+ifndef NACL_ARCH
+	$(error Cannot run in sel_ldr unless $$NACL_ARCH is set)
+endif
+	$(SEL_LDR_PATH) -d $(SEL_LDR_ARGS) $(OUTDIR)/$(TARGET)_$(NACL_ARCH).nexe -- $(EXE_ARGS)
+endif