build: fix kernel 5.4 on macos

As part of the kernel build process there are utilities built to run on
the host system that expect linux kernel headers to be available.
Unfortunately macos/darwin doesn't have these headers.

vdso2c requires types.h so provide a minimal stub to satisfy it.

Signed-off-by: Kevin Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>

tools/Makefile

@@ -138,6 +138,10 @@ $(STAGING_DIR_HOST)/.prepared: $(TMP_DIR)/.build
 	mkdir -p $(BUILD_DIR_HOST)/stamp $(STAGING_DIR_HOST)/include/sys
 	$(INSTALL_DATA) $(TOPDIR)/tools/include/*.h $(STAGING_DIR_HOST)/include/
 	$(INSTALL_DATA) $(TOPDIR)/tools/include/sys/*.h $(STAGING_DIR_HOST)/include/sys/
+ifneq ($(HOST_OS),Linux)
+	mkdir -p $(STAGING_DIR_HOST)/include/asm
+	$(INSTALL_DATA) $(TOPDIR)/tools/include/asm/*.h $(STAGING_DIR_HOST)/include/asm/
+endif
 	ln -snf lib $(STAGING_DIR_HOST)/lib64
 	touch $@
 

tools/include/asm/types.h

+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * asm-generic/int-ll64.h
+ *
+ * Integer declarations for architectures which use "long long"
+ * for 64-bit types.
+ */
+
+#ifndef _ASM_GENERIC_INT_LL64_H
+#define _ASM_GENERIC_INT_LL64_H
+
+typedef __signed__ char __s8;
+
+typedef __signed__ short __s16;
+
+typedef __signed__ int __s32;
+
+#ifdef __GNUC__
+__extension__ typedef __signed__ long long __s64;
+#else
+typedef __signed__ long long __s64;
+#endif
+
+#endif /* _ASM_GENERIC_INT_LL64_H */