arm: hevcdsp: Avoid using macro expansion counters

Clang supports the macro expansion counter (used for making unique
labels within macro expansions), but not when targeting darwin.

Convert uses of the counter into normal local labels, as used
elsewhere.

Since Xcode 9.3, the bundled clang supports altmacro and doesn't
require using gas-preprocessor any longer.
Signed-off-by: Martin Storsjö <martin@martin.st>

libavcodec/arm/hevcdsp_deblock_neon.S

@@ -152,7 +152,7 @@
 
         and        r9, r8, r7
         cmp        r9, #0
-        beq        weakfilter_\@
+        beq        1f
 
         vadd.i16  q2, q11, q12
         vadd.i16  q4, q9, q8
@@ -210,11 +210,11 @@
         vbit      q13, q3, q5
         vbit      q14, q2, q5
 
-weakfilter_\@:
+1:
         mvn       r8, r8
         and       r9, r8, r7
         cmp       r9, #0
-        beq       ready_\@
+        beq       2f
 
         vdup.16    q4, r2
 
@@ -275,7 +275,7 @@ weakfilter_\@:
         vbit      q11, q0, q5
         vbit      q12, q4, q5
 
-ready_\@:
+2:
         vqmovun.s16 d16, q8
         vqmovun.s16 d18, q9
         vqmovun.s16 d20, q10