Everywhere: Re-format with clang-format-11

Compared to version 10 this fixes a bunch of formatting issues, mostly
around structs/classes with attributes like [[gnu::packed]], and
incorrect insertion of spaces in parameter types ("T &"/"T &&").
I also removed a bunch of // clang-format off/on and FIXME comments that
are no longer relevant - on the other hand it tried to destroy a couple of
neatly formatted comments, so I had to add some as well.

Libraries/LibELF/AuxiliaryVector.h

@@ -40,6 +40,7 @@ typedef struct
     } a_un;
 } auxv_t;
 
+// clang-format off
 #define AT_NULL 0           /* No length, last entry's a_type has this value */
 #define AT_IGNORE 1         /* Entry has no meaning, a_un undefined */
 #define AT_EXECFD 2         /* a_val contains a file descriptor of the main program image */
@@ -65,6 +66,7 @@ typedef struct
 #define AT_EXECFN 31        /* a_ptr points to file name of executed program */
 #define AT_EXE_BASE 32      /* a_ptr holds base address where main program was loaded into memory */
 #define AT_EXE_SIZE 33      /* a_val holds the size of the main program in memory */
+// clang-format on
 
 namespace ELF {