[sanitizer_common] Fix devname_r() return type on !NetBSD

[mgorny]

Summary

Update the interceptor for devname_r() to account for correct return
types on different platforms. This function returns int on NetBSD
but char* on FreeBSD/OSX. Noticed by @krytarowski.

[mgorny]

Fixed lint.

[krytarowski]

Looks fine, but according to newer style of newer interceptors we prefer: DEVNAME_R_RETTYPE res = REAL(devname_r)(dev, type, path, len);

[mgorny]

Updated variable style.

compiler-rt/trunk/lib/sanitizer_common/sanitizer_common_interceptors.inc

INTERCEPTOR(char *, devname, u64 dev, u32 type) {
   return name;
 }
 #define INIT_DEVNAME COMMON_INTERCEPT_FUNCTION(devname);
 #else
 #define INIT_DEVNAME
 #endif
 
 #if SANITIZER_INTERCEPT_DEVNAME_R
-INTERCEPTOR(int, devname_r, u64 dev, u32 type, char *path, uptr len) {
+#if SANITIZER_NETBSD
+#define DEVNAME_R_RETTYPE int
+#define DEVNAME_R_SUCCESS(x) (!(x))
+#else
+#define DEVNAME_R_RETTYPE char*
+#define DEVNAME_R_SUCCESS(x) (x)
+#endif
+INTERCEPTOR(DEVNAME_R_RETTYPE, devname_r, u64 dev, u32 type, char *path,
+            uptr len) {
   void *ctx;
-  int res;
   COMMON_INTERCEPTOR_ENTER(ctx, devname_r, dev, type, path, len);
-  res = REAL(devname_r)(dev, type, path, len);
-  if (!res)
+  DEVNAME_R_RETTYPE res = REAL(devname_r)(dev, type, path, len);
+  if (DEVNAME_R_SUCCESS(res))
     COMMON_INTERCEPTOR_WRITE_RANGE(ctx, path, REAL(strlen)(path) + 1);
   return res;
 }
 #define INIT_DEVNAME_R COMMON_INTERCEPT_FUNCTION(devname_r);
 #else
 #define INIT_DEVNAME_R
 #endif