lavu/riscv: align functions to 4 bytes

Currently the start of the byte range for each function is aligned to
4 bytes. But this can lead to situations whence the function is preceded
by a 2-byte C.NOP at the aligned 4-byte boundary. Then the first actual
instruction and the function symbol are only aligned on 2 bytes.

This forcefully disables compression for the alignment and the symbol,
thus ensuring that there is no padding before the function.

libavutil/riscv/asm.S

@@ -50,14 +50,17 @@
 
         .macro func sym, exts:vararg
             .text
-            .align 2
             .option push
             archadd \exts
 
             .global \sym
             .hidden \sym
             .type   \sym, %function
+            .option push
+            .option norvc
+            .align  2
             \sym:
+            .option pop
 
             .macro endfunc
                 .size   \sym, . - \sym