Revert "Add 'Android.mk' file, fix compile on Android."

Fails compile on x86_64, arm64, mips64. Failures have been identified, will re-upload on Monday.

This reverts commit b9a322d86635c5b1358af0d46a8be1021f4ddb60.

Change-Id: I14b35a3aae618da4ff108328a499505893c15568
diff --git a/libminijail.c b/libminijail.c
index 1c54a40..0dab24d 100644
--- a/libminijail.c
+++ b/libminijail.c
@@ -36,7 +36,7 @@
 #include "libminijail.h"
 #include "libminijail-private.h"
 
-#include "signal_handler.h"
+#include "signal.h"
 #include "syscall_filter.h"
 #include "util.h"
 
@@ -203,14 +203,9 @@
 
 int API minijail_change_group(struct minijail *j, const char *group)
 {
-	struct group *pgr = NULL;
-
-#if defined(__BRILLO__)
-	/* Android does not implement getgrnam_r(). */
-	pgr = getgrnam(group);
-#else
-	struct group gr;
 	char *buf = NULL;
+	struct group gr;
+	struct group *pgr = NULL;
 	ssize_t sz = sysconf(_SC_GETGR_R_SIZE_MAX);
 	if (sz == -1)
 		sz = 65536;	/* and mine is as good as yours, really */
@@ -230,7 +225,6 @@
 	 */
 	free(buf);
 	/* getgrnam_r(3) does *not* set errno when |pgr| is NULL. */
-#endif
 	if (!pgr)
 		return -1;
 	minijail_change_gid(j, pgr->gr_gid);
@@ -689,13 +683,6 @@
 
 void drop_caps(const struct minijail *j)
 {
-#if defined(__BRILLO__)
-	/*
-	 * Temporarily disable capabilities support until Minijail can use
-	 * libcap-ng.
-	 */
-	(void) j;
-#else
 	cap_t caps = cap_get_proc();
 	cap_value_t flag[1];
 	const uint64_t one = 1;
@@ -751,7 +738,6 @@
 		die("can't apply final cleaned capset");
 
 	cap_free(caps);
-#endif
 }
 
 void set_seccomp_filter(const struct minijail *j)
@@ -957,10 +943,6 @@
 
 int setup_preload(void)
 {
-#if defined(__BRILLO__)
-	/* Don't use LDPRELOAD on Brillo. */
-	return 0;
-#else
 	char *oldenv = getenv(kLdPreloadEnvVar) ? : "";
 	char *newenv = malloc(strlen(oldenv) + 2 + strlen(PRELOADPATH));
 	if (!newenv)
@@ -974,7 +956,6 @@
 	setenv(kLdPreloadEnvVar, newenv, 1);
 	free(newenv);
 	return 0;
-#endif
 }
 
 int setup_pipe(int fds[2])