kernel: fix linux 4.9 host tools portability issues

Signed-off-by: Felix Fietkau <nbd@nbd.name>

tools/build/Build.include

@@ -95,4 +95,4 @@ cxx_flags = -Wp,-MD,$(depfile),-MT,$@ $(CXXFLAGS) -D"BUILD_STR(s)=\#s" $(CXXFLAG
 ###
 ## HOSTCC C flags
 
-host_c_flags = -Wp,-MD,$(depfile),-MT,$@ $(CHOSTFLAGS) -D"BUILD_STR(s)=\#s" $(CHOSTFLAGS_$(basetarget).o) $(CHOSTFLAGS_$(obj))
+host_c_flags = -MD -MF $(depfile) -MT $@ $(CHOSTFLAGS) -D"BUILD_STR(s)=\#s" $(CHOSTFLAGS_$(basetarget).o) $(CHOSTFLAGS_$(obj))

tools/perf/pmu-events/jevents.c

@@ -35,6 +35,7 @@
 #include <stdlib.h>
 #include <errno.h>
 #include <string.h>
+#include <strings.h>
 #include <ctype.h>
 #include <unistd.h>
 #include <stdarg.h>

tools/perf/pmu-events/json.c

@@ -38,7 +38,6 @@
 #include <unistd.h>
 #include "jsmn.h"
 #include "json.h"
-#include <linux/kernel.h>
 
 
 static char *mapfile(const char *fn, size_t *size)