Don't expose all BSD extensions.

Just expose the ones that bionic historically leaked.

Also, many of the M_* constants in <math.h> are actually POSIX.

Change-Id: I6275df84c5866b872b71f1c8ed14e2aada12b793
diff --git a/libc/include/sys/cdefs.h b/libc/include/sys/cdefs.h
index 5369e30..8cde1c7 100644
--- a/libc/include/sys/cdefs.h
+++ b/libc/include/sys/cdefs.h
@@ -233,11 +233,6 @@
 # define __USE_BSD 1
 #endif
 
-/* Historically there was no way to turn off the BSD stuff, so we're probably stuck with that. */
-#if !defined(__USE_BSD)
-# define __USE_BSD 1
-#endif
-
 /* _FILE_OFFSET_BITS 64 support. */
 #if !defined(__LP64__) && defined(_FILE_OFFSET_BITS)
 #if _FILE_OFFSET_BITS == 64
diff --git a/libc/include/sys/endian.h b/libc/include/sys/endian.h
index 99d5ff1..b9e4758 100644
--- a/libc/include/sys/endian.h
+++ b/libc/include/sys/endian.h
@@ -64,7 +64,7 @@
 #define htonq(x) __swap64(x)
 #define ntohq(x) __swap64(x)
 
-#if defined(__USE_BSD)
+#if defined(__USE_BSD) || defined(__BIONIC__) /* Historically bionic exposed these. */
 #define LITTLE_ENDIAN _LITTLE_ENDIAN
 #define BIG_ENDIAN _BIG_ENDIAN
 #define PDP_ENDIAN _PDP_ENDIAN
diff --git a/libc/include/sys/limits.h b/libc/include/sys/limits.h
index b7d899b..5aa3d80 100644
--- a/libc/include/sys/limits.h
+++ b/libc/include/sys/limits.h
@@ -73,7 +73,7 @@
 # define LLONG_MIN	(-0x7fffffffffffffffLL-1)
 					/* min value for a signed long long */
 
-#if defined(__USE_BSD)
+#if defined(__USE_BSD) || defined(__BIONIC__) /* Historically bionic exposed these. */
 # define UID_MAX	UINT_MAX	/* max value for a uid_t */
 # define GID_MAX	UINT_MAX	/* max value for a gid_t */
 #endif
diff --git a/libc/include/sys/types.h b/libc/include/sys/types.h
index 469842d..2895057 100644
--- a/libc/include/sys/types.h
+++ b/libc/include/sys/types.h
@@ -141,7 +141,7 @@
 typedef unsigned int        uint_t;
 typedef unsigned int        uint;
 
-#if defined(__USE_BSD)
+#if defined(__USE_BSD) || defined(__BIONIC__) /* Historically bionic exposed these. */
 #include <sys/sysmacros.h>
 
 typedef unsigned char  u_char;