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.

Kernel/UnixTypes.h

@@ -604,6 +604,8 @@ struct ifreq {
         void* ifru_data;
         unsigned int ifru_index;
     } ifr_ifru;
+
+    // clang-format off
 #define ifr_addr ifr_ifru.ifru_addr           // address
 #define ifr_dstaddr ifr_ifru.ifru_dstaddr     // other end of p-to-p link
 #define ifr_broadaddr ifr_ifru.ifru_broadaddr // broadcast address
@@ -620,6 +622,7 @@ struct ifreq {
 #define ifr_index ifr_ifru.ifru_index         // interface index
 #define ifr_llprio ifr_ifru.ifru_metric       // link layer priority
 #define ifr_hwaddr ifr_ifru.ifru_hwaddr       // MAC address
+    // clang-format on
 };
 
 struct rtentry {