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

This requires disabling LDPRELOAD and temporarily disabling
capabilities support.

Reland of https://android-review.googlesource.com/#/c/159755/
with compile fixes. Compile-tested on
aosp_{x86,x86_64,arm,arm64,mips64}-eng.

Bug: 22487289
Change-Id: Ia4530cf09b074aa0a2afe5a5b307ff3c5c5d6c08
diff --git a/gen_syscalls.sh b/gen_syscalls.sh
index 3121b42..a01d500 100755
--- a/gen_syscalls.sh
+++ b/gen_syscalls.sh
@@ -12,18 +12,13 @@
 
 set -e
 
-if [ $# -ne 1 ] && [ $# -ne 3 ]; then
-  echo "Usage: $(basename "$0") OUTFILE"
-  echo "Usage: $(basename "$0") CC CFLAGS OUTFILE"
+if [ $# -ne 2 ]; then
+  echo "Usage: $(basename "$0") CC OUTFILE"
   exit 1
 fi
 
-if [ $# -eq 3 ]; then
-  CC="$1"
-  shift
-  CFLAGS="$1"
-  shift
-fi
+CC="$1"
+shift
 OUTFILE="$1"
 
 # sed expression which extracts system calls that are
@@ -43,7 +38,7 @@
 #include "libsyscalls.h"
 const struct syscall_entry syscall_table[] = {
 $(echo '#include <asm/unistd.h>' | \
-  ${CC} ${CFLAGS} -dD - -E | sed -rne "${SED_MULTILINE}")
+  ${CC} -dD - -E | sed -rne "${SED_MULTILINE}")
   { NULL, -1 },
 };
 EOF