Unified sysroot: kill arch-specific include dirs.

<machine/asm.h> was internal use only.

<machine/fenv.h> is quite large, but can live in <bits/...>.

<machine/regdef.h> is trivially replaced by saying $x instead of x in
our assembler.

<machine/setjmp.h> is trivially inlined into <setjmp.h>.

<sgidefs.h> is unused.

Bug: N/A
Test: builds
Change-Id: Id05dbab43a2f9537486efb8f27a5ef167b055815
diff --git a/libc/private/bionic_asm.h b/libc/private/bionic_asm.h
index c1fab1f..92f38aa 100644
--- a/libc/private/bionic_asm.h
+++ b/libc/private/bionic_asm.h
@@ -36,7 +36,17 @@
 #define __bionic_asm_custom_end(f)
 #define __bionic_asm_function_type @function
 
-#include <machine/asm.h>
+#if defined(__aarch64__)
+#include <private/bionic_asm_arm64.h>
+#elif defined(__arm__)
+#include <private/bionic_asm_arm.h>
+#elif defined(__i386__)
+#include <private/bionic_asm_x86.h>
+#elif defined(__mips__)
+#include <private/bionic_asm_mips.h>
+#elif defined(__x86_64__)
+#include <private/bionic_asm_x86_64.h>
+#endif
 
 #define ENTRY_NO_DWARF(f) \
     .text; \
@@ -72,4 +82,4 @@
     .globl alias; \
     .equ alias, original
 
-#endif /* _PRIVATE_BIONIC_ASM_H_ */
+#endif