Fix bsaes-armv7.pl getting disabled by accident.

https://boringssl-review.googlesource.com/c/34188 accidentally disabled
it (__ARM_MAX_ARCH__ wasn't defined), which, in turn, masked a bug in
https://boringssl-review.googlesource.com/c/34874.

Remove the __ARM_MAX_ARCH__ check as that's hardcoded to 8 anyway. Then
revert the problematic part of the bsaes-armv7.pl change. That brings
back the somewhat questionable post-dispatch to pre-dispatch call, but I
hope to patch the fallbacks out soon anyway.

Change-Id: I567e55fe35cb716d5ed56580113a302617f5ad71
Reviewed-on: https://boringssl-review.googlesource.com/c/35044
Commit-Queue: David Benjamin <davidben@google.com>
Commit-Queue: Adam Langley <agl@google.com>
Reviewed-by: Adam Langley <agl@google.com>

crypto/fipsmodule/aes/asm/bsaes-armv7.pl

@@ -1113,7 +1113,10 @@ my ($inp,$out,$len,$key, $ivp,$fp,$rounds)=map("r$_",(0..3,8..10));
 my ($keysched)=("sp");
 
 $code.=<<___;
-.extern aes_nohw_cbc_encrypt
+@ TODO(davidben): This should be aes_nohw_cbc_encrypt, but that function does
+@ not exist. Rather than add it, patch this fallback out. See
+@ https://crbug.com/boringssl/256.
+.extern AES_cbc_encrypt
 .extern aes_nohw_decrypt
 
 .global	bsaes_cbc_encrypt
@@ -1123,10 +1126,10 @@ bsaes_cbc_encrypt:
 #ifndef	__KERNEL__
 	cmp	$len, #128
 #ifndef	__thumb__
-	blo	aes_nohw_cbc_encrypt
+	blo	AES_cbc_encrypt
 #else
 	bhs	1f
-	b	aes_nohw_cbc_encrypt
+	b	AES_cbc_encrypt
 1:
 #endif
 #endif

crypto/fipsmodule/aes/internal.h

@@ -49,7 +49,7 @@ OPENSSL_INLINE char bsaes_capable(void) { return vpaes_capable(); }
 
 OPENSSL_INLINE int hwaes_capable(void) { return CRYPTO_is_ARMv8_AES_capable(); }
 
-#if defined(OPENSSL_ARM) && __ARM_MAX_ARCH__ >= 7
+#if defined(OPENSSL_ARM)
 #define BSAES
 OPENSSL_INLINE char bsaes_capable(void) { return CRYPTO_is_NEON_capable(); }
 #endif

crypto/fipsmodule/cipher/e_aes.c

@@ -64,10 +64,6 @@
 #include "../modes/internal.h"
 #include "../delocate.h"
 
-#if defined(OPENSSL_ARM) || defined(OPENSSL_AARCH64)
-#include <openssl/arm_arch.h>
-#endif
-
 
 OPENSSL_MSVC_PRAGMA(warning(push))
 OPENSSL_MSVC_PRAGMA(warning(disable: 4702))  // Unreachable code.