Use .p2align in ASMALIGN() macro

The test for .align syntax was apparently unreliable with some compilers.
Using the .p2align directive instead avoids the need for this test.

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@23428 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

configure

@@ -2794,9 +2794,6 @@ if enabled gprof; then
     add_ldflags -p
 fi
 
-# Find out if the .align argument is a power of two or not.
-check_asm asmalign_pot '".align 3"'
-
 enabled_any $THREADS_LIST      && enable threads
 
 check_deps $CONFIG_LIST       \
@@ -2819,7 +2816,6 @@ enabled asm || { arch=c; disable $ARCH_LIST $ARCH_EXT_LIST; }
 echo "install prefix            $prefix"
 echo "source path               $source_path"
 echo "C compiler                $cc"
-echo ".align is power-of-two    $asmalign_pot"
 echo "ARCH                      $arch ($cpu)"
 if test "$build_suffix" != ""; then
     echo "build suffix              $build_suffix"
@@ -3051,8 +3047,6 @@ get_version LIBAVFORMAT libavformat/avformat.h
 get_version LIBAVUTIL   libavutil/avutil.h
 get_version LIBAVFILTER libavfilter/avfilter.h
 
-enabled asmalign_pot || align_shift="1 <<"
-
 cat > $TMPH <<EOF
 /* Automatically generated by configure - do not modify! */
 #ifndef FFMPEG_CONFIG_H
@@ -3063,7 +3057,7 @@ cat > $TMPH <<EOF
 #define CC_TYPE "$cc_type"
 #define CC_VERSION $cc_version
 #define restrict $_restrict
-#define ASMALIGN(ZEROBITS) ".align $align_shift " #ZEROBITS "\\n\\t"
+#define ASMALIGN(ZEROBITS) ".p2align " #ZEROBITS "\\n\\t"
 #define EXTERN_PREFIX "${extern_prefix}"
 #define EXTERN_ASM ${extern_prefix}
 EOF