dhcpcd-6.8.2: do not use switch_user() in Brillo builds

Brillo builds can use minijail to change dhcpcd-6.8.2 uid and
gid, so do not use switch_user() in these builds.

BUG: 25083940
Change-Id: I175191142015298db1909ee660d2a67672a4508c
TEST: dhcpcd-6.8.2 runs as expected during weaved setup in brillo build.
diff --git a/dhcpcd.c b/dhcpcd.c
index e0908cf..28a472c 100644
--- a/dhcpcd.c
+++ b/dhcpcd.c
@@ -53,7 +53,7 @@
 #include <sys/capability.h>
 #include <sys/prctl.h>
 #include <private/android_filesystem_config.h>
-#endif /* __ANDROID__ */
+#endif  /* __ANDROID__ */
 
 #include "config.h"
 #include "arp.h"
@@ -1426,7 +1426,7 @@
 	cap.inheritable = 0;
 	capset(&header, &cap);
 }
-#endif /* __ANDROID__ */
+#endif  /* __ANDROID__ */
 
 int
 main(int argc, char **argv)
@@ -1447,9 +1447,9 @@
 #endif
 	char ifn[IF_NAMESIZE];
 
-#if defined(__ANDROID__)
+#if defined(__ANDROID__) && !defined(__BRILLO__)
 	switch_user();
-#endif  // __ANDROID__
+#endif  /* __ANDROID__ && !__BRILLO__ */
 
 	/* Test for --help and --version */
 	if (argc > 1) {