More compat work. Rename libraries from LibFoo.a => libfoo.a

This makes it more straightforward to build a cross-compiler toolchain.
Also move math stuff from LibC to LibM.

Kernel/Syscall.h

@@ -1,6 +1,7 @@
 #pragma once
 
 #include <AK/Types.h>
+#include <LibC/fd_set.h>
 
 #define ENUMERATE_SYSCALLS \
     __ENUMERATE_SYSCALL(sleep) \
@@ -83,10 +84,6 @@
     __ENUMERATE_SYSCALL(link) \
 
 
-#ifdef SERENITY
-struct fd_set;
-#endif
-
 namespace Syscall {
 
 enum Function {

Kernel/UnixTypes.h

@@ -1,8 +1,5 @@
 #pragma once
 
-#define FD_SETSIZE 64
-struct fd_set { unsigned char bits[FD_SETSIZE / 8];  };
-
 #define WNOHANG 1
 
 #define SIG_DFL ((void*)0)

Kernel/makeall.sh

@@ -4,8 +4,15 @@ sudo id
 
 make_cmd="make -j2"
 
+rm -r ../Root/usr && \
 $make_cmd -C ../LibC clean && \
 $make_cmd -C ../LibC && \
+(cd ../LibC && ./install.sh) && \
+$make_cmd -C ../LibM clean && \
+$make_cmd -C ../LibM && \
+(cd ../LibM && ./install.sh) && \
+$make_cmd -C ../LibM clean && \
+$make_cmd -C ../LibM clean && \
 $make_cmd -C ../LibGUI clean && \
 $make_cmd -C ../LibGUI && \
 $make_cmd -C ../Userland clean && \