Makefile: Move NETNS_RUN_DIR definition to C code

NETNS_RUN_DIR is set in the Makefile, then passed into the C code with
-D.  But NETNS_RUN_DIR is just a fixed string, it doesn't depend on any
make probes or variables, so there's really no reason to handle it via the
Makefile.  Just move it to a plain #define in conf.c.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

Makefile

@@ -44,7 +44,6 @@ FLAGS := -Wall -Wextra -Wno-format-zero-length
 FLAGS += -pedantic -std=c11 -D_XOPEN_SOURCE=700 -D_GNU_SOURCE
 FLAGS +=  $(FORTIFY_FLAG) -O2 -pie -fPIE
 FLAGS += -DPAGE_SIZE=$(shell getconf PAGE_SIZE)
-FLAGS += -DNETNS_RUN_DIR=\"/run/netns\"
 FLAGS += -DPASST_AUDIT_ARCH=AUDIT_ARCH_$(AUDIT_ARCH)
 FLAGS += -DRLIMIT_STACK_VAL=$(RLIMIT_STACK_VAL)
 FLAGS += -DARCH=\"$(TARGET_ARCH)\"

conf.c

@@ -46,6 +46,8 @@
 #include "isolation.h"
 #include "log.h"
 
+#define NETNS_RUN_DIR	"/run/netns"
+
 /**
  * next_chunk - Return the next piece of a string delimited by a character
  * @s:		String to search