Remove stray underscores.

https://boringssl-review.googlesource.com/c/33424 missed a line.

I'm not sure why this runs right now. It errors if we turn the shaext
and avx2 code on. (NB: We shouldn't turn on AVX2 code without fixing its
CFI annotations. They're broken. It appears to allocates stack in a
loop.)

Change-Id: I17daa72aae8aad879c338433340155c331122397
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/35824
Commit-Queue: David Benjamin <davidben@google.com>
Commit-Queue: Adam Langley <agl@google.com>
Reviewed-by: Adam Langley <agl@google.com>
diff --git a/crypto/fipsmodule/sha/asm/sha512-x86_64.pl b/crypto/fipsmodule/sha/asm/sha512-x86_64.pl
index ca827a6..8c5a5f3 100755
--- a/crypto/fipsmodule/sha/asm/sha512-x86_64.pl
+++ b/crypto/fipsmodule/sha/asm/sha512-x86_64.pl
@@ -278,7 +278,6 @@
 	jnz	_shaext_shortcut
 ___
     # XOP codepath removed.
-___
 $code.=<<___ if ($avx>1);
 	and	\$`1<<8|1<<5|1<<3`,%r11d	# check for BMI2+AVX2+BMI1
 	cmp	\$`1<<8|1<<5|1<<3`,%r11d