Support malloc() on bare metal

Your Actually Portable Executables now contains a simple virtual memory
that works similarly to the Linux Kernel in the sense that it maps your
physical memory to negative addresses. This is needed to support mmap()
and malloc(). This functionality has zero code size impact. For example
the MODE=tiny LIFE.COM executable is still only 12KB in size.

The APE bootloader code has also been simplified to improve readibility
and further elevate the elegance by which we're able to support so many
platforms thereby enhancing verifiability so that we may engender trust
in this bootloading process.

libc/dce.h

@@ -20,7 +20,6 @@
 #define OPENBSD 16
 #define FREEBSD 32
 #define NETBSD  64
-#define UEFI    128
 
 #ifdef NDEBUG
 #define NoDebug() 1
@@ -73,7 +72,6 @@
 #define SupportsLinux()   ((SUPPORT_VECTOR & LINUX) == LINUX)
 #define SupportsMetal()   ((SUPPORT_VECTOR & METAL) == METAL)
 #define SupportsWindows() ((SUPPORT_VECTOR & WINDOWS) == WINDOWS)
-#define SupportsUefi()    ((SUPPORT_VECTOR & UEFI) == UEFI)
 #define SupportsXnu()     ((SUPPORT_VECTOR & XNU) == XNU)
 #define SupportsFreebsd() ((SUPPORT_VECTOR & FREEBSD) == FREEBSD)
 #define SupportsOpenbsd() ((SUPPORT_VECTOR & OPENBSD) == OPENBSD)
@@ -86,7 +84,6 @@
 #define IsLinux()   (SupportsLinux() && (__hostos & LINUX))
 #define IsMetal()   (SupportsMetal() && (__hostos & METAL))
 #define IsWindows() (SupportsWindows() && (__hostos & WINDOWS))
-#define IsUefi()    (SupportsUefi() && (__hostos & UEFI))
 #define IsXnu()     (SupportsXnu() && (__hostos & XNU))
 #define IsFreebsd() (SupportsFreebsd() && (__hostos & FREEBSD))
 #define IsOpenbsd() (SupportsOpenbsd() && (__hostos & OPENBSD))
@@ -97,7 +94,6 @@
 #define IsLinux() $LINUX,__hostos(%rip)
 #define IsMetal() $METAL,__hostos(%rip)
 #define IsWindows() $WINDOWS,__hostos(%rip)
-#define IsUefi() $UEFI,__hostos(%rip)
 #define IsBsd() $XNU|FREEBSD|OPENBSD|NETBSD,__hostos(%rip)
 #define IsXnu() $XNU,__hostos(%rip)
 #define IsFreebsd() $FREEBSD,__hostos(%rip)