Fixes to makefiles while building (netdata#242)

* makefile: dont fail if `rm` cant find any output.

* make tools/complement.sh script executable

* makefile: use KERNELSOURCE and not /usr/src/linux

/usr/src/linux is not always the correct location; it is modifiable by
KERNELSOURCE.

Makefile

@@ -26,9 +26,9 @@ $(KERNEL_PROGRAM):
 	cd $(KERNEL_DIR) && $(MAKE) all;
 
 clean:
-	rm *.o;
+	rm -f *.o;
 	cd $(KERNEL_DIR) && $(MAKE) clean;
-	rm artifacts/*
+	rm -f artifacts/*
 
 install:
 	cp *netdata_ebpf_process.$(VER_MAJOR).$(VER_MINOR).o /usr/libexec/netdata/plugins.d/

kernel/Makefile

@@ -23,8 +23,8 @@ CLANG_VERSION := $(shell clang --version | grep -o -E 'clang version [0-9]+\.[0-
 LLVM_INCLUDES = $(shell [ -d /usr/lib/clang ] && echo "-I/usr/lib/clang/$(CLANG_VERSION)/include" || echo "-I/usr/lib64/clang/$(CLANG_VERSION)/include")
 LLVM_INCLUDES += -I/opt/rh/llvm-toolset-7.0/root/usr/lib64/clang/$(CLANG_VERSION)/include
 
-#KERNEL_VERSION="$(shell basename $(realpath /usr/src/linux) | cut -f 2 -d '-')"
-KERNEL_VERSION="$(shell cat /usr/src/linux/include/config/kernel.release)"
+#KERNEL_VERSION="$(shell basename $(realpath $(KERNELSOURCE)) | cut -f 2 -d '-')"
+KERNEL_VERSION="$(shell cat $(KERNELSOURCE)/include/config/kernel.release)"
 
 VER_MAJOR=$(shell echo $(KERNEL_VERSION) | cut -d. -f1)
 VER_MINOR=$(shell echo $(KERNEL_VERSION) | cut -d. -f2)
@@ -54,7 +54,7 @@ NETDATA_APPS= cachestat \
 all: $(NETDATA_APPS)
 
 %_kern.o: %_kern.c
-	if [ -w /usr/src/linux/include/generated/autoconf.h ]; then  if [ "$(CURRENT_KERNEL)" -ge 328448 ]; then sed -i -e 's/\(#define CONFIG_CC_HAS_ASM_INLINE 1\)/\/\/\1/' /usr/src/linux/include/generated/autoconf.h; fi ; fi
+	if [ -w $(KERNELSOURCE)/include/generated/autoconf.h ]; then  if [ "$(CURRENT_KERNEL)" -ge 328448 ]; then sed -i -e 's/\(#define CONFIG_CC_HAS_ASM_INLINE 1\)/\/\/\1/' $(KERNELSOURCE)/include/generated/autoconf.h; fi ; fi
 	$(CLANG) $(EXTRA_CFLAGS) -S -nostdinc $(LINUXINCLUDE) $(LLVM_INCLUDES) \
 		-D__KERNEL__ -D__ASM_SYSREG_H -Wno-unused-value -Wno-pointer-sign \
 	    	-Wno-compare-distinct-pointer-types \
@@ -90,4 +90,4 @@ all: $(NETDATA_APPS)
 $(NETDATA_APPS): %: %_kern.o
 
 clean:
-	rm *.o *.ll
+	rm -f *.o *.ll