fallocate: remove uClibc workaround to benefit macOS.

My understanding is that uClibc is dead, and the probe for fallocate
would need to be made more complicated to work for macOS (where we fake
posix_fallocate() in lib/portability.c).

scripts/genconfig.sh

@@ -52,11 +52,6 @@ EOF
   probesymbol TOYBOX_ICONV -c << EOF
     #include "iconv.h"
 EOF
-  probesymbol TOYBOX_FALLOCATE << EOF
-    #include <fcntl.h>
-
-    int main(int argc, char *argv[]) { return posix_fallocate(0,0,0); }
-EOF
 
   # Android and some other platforms miss utmpx
   probesymbol TOYBOX_UTMPX -c << EOF

toys/other/fallocate.c

@@ -8,7 +8,6 @@ USE_FALLOCATE(NEWTOY(fallocate, ">1l#|o#", TOYFLAG_USR|TOYFLAG_BIN))
 
 config FALLOCATE
   bool "fallocate"
-  depends on TOYBOX_FALLOCATE
   default y
   help
     usage: fallocate [-l size] [-o offset] file