Employ consistent LIBAV_COMPAT_ multiple inclusion guards in compat/

Also fix a comment and an #endif comment.

compat/aix/math.h

-/*
- * Workaround aix-specific class() function clashing with libav class usage
- */
+/* Work around the class() function in AIX math.h clashing with identifiers
+ * named "class". */
 
-#ifndef COMPAT_AIX_MATH_H
-#define COMPAT_AIX_MATH_H
+#ifndef LIBAV_COMPAT_AIX_MATH_H
+#define LIBAV_COMPAT_AIX_MATH_H
 
 #define class class_in_math_h_causes_problems
 
@@ -11,4 +10,4 @@
 
 #undef class
 
-#endif /* COMPAT_AIX_MATH_H */
+#endif /* LIBAV_COMPAT_AIX_MATH_H */

compat/tms470/math.h

+#ifndef LIBAV_COMPAT_TMS470_MATH_H
+#define LIBAV_COMPAT_TMS470_MATH_H
+
 #include_next <math.h>
 
 #undef INFINITY
@@ -5,3 +8,5 @@
 
 #define INFINITY (*(const float*)((const unsigned []){ 0x7f800000 }))
 #define NAN      (*(const float*)((const unsigned []){ 0x7fc00000 }))
+
+#endif /* LIBAV_COMPAT_TMS470_MATH_H */

compat/w32pthreads.h

@@ -26,8 +26,8 @@
  * w32threads to pthreads wrapper
  */
 
-#ifndef LIBAV_W32PTHREADS_H
-#define LIBAV_W32PTHREADS_H
+#ifndef LIBAV_COMPAT_W32PTHREADS_H
+#define LIBAV_COMPAT_W32PTHREADS_H
 
 /* Build up a pthread-like API using underlying Windows API. Have only static
  * methods so as to not conflict with a potentially linked in pthread-win32
@@ -276,4 +276,4 @@ static void w32thread_init(void)
 
 }
 
-#endif /* LIBAV_W32PTHREADS_H */
+#endif /* LIBAV_COMPAT_W32PTHREADS_H */

libavutil/arm/cpu.h

@@ -29,4 +29,4 @@
 #define have_vfpv3(flags)   (HAVE_VFPV3   && ((flags) & AV_CPU_FLAG_VFPV3))
 #define have_neon(flags)    (HAVE_NEON    && ((flags) & AV_CPU_FLAG_NEON))
 
-#endif
+#endif /* AVUTIL_ARM_CPU_H */