Split libc_debug.so into two .so modules loaded on demand from libc.so

This change is intended to eliminate need to replace libc.so with libc_debug.so in order to enablememory allocation debugging.
This is also the first step towards implementing extended memoryallocation debugging using emulator's capabilities in monitoring memory access.
diff --git a/libc/bionic/dlmalloc.c b/libc/bionic/dlmalloc.c
index f6f878e..19fbb75 100644
--- a/libc/bionic/dlmalloc.c
+++ b/libc/bionic/dlmalloc.c
@@ -390,9 +390,9 @@
   size_t. The value is used only if  HAVE_USR_INCLUDE_MALLOC_H is not set
 
 REALLOC_ZERO_BYTES_FREES    default: not defined
-  This should be set if a call to realloc with zero bytes should 
-  be the same as a call to free. Some people think it should. Otherwise, 
-  since this malloc returns a unique pointer for malloc(0), so does 
+  This should be set if a call to realloc with zero bytes should
+  be the same as a call to free. Some people think it should. Otherwise,
+  since this malloc returns a unique pointer for malloc(0), so does
   realloc(p, 0).
 
 LACKS_UNISTD_H, LACKS_FCNTL_H, LACKS_SYS_PARAM_H, LACKS_SYS_MMAN_H
@@ -671,7 +671,7 @@
 /* ------------------- Declarations of public routines ------------------- */
 
 /* Check an additional macro for the five primary functions */
-#if !defined(USE_DL_PREFIX) || !defined(MALLOC_LEAK_CHECK) 
+#ifndef USE_DL_PREFIX
 #define dlcalloc               calloc
 #define dlfree                 free
 #define dlmalloc               malloc
@@ -3627,7 +3627,7 @@
       m->seg.sflags = mmap_flag;
       m->magic = mparams.magic;
       init_bins(m);
-      if (is_global(m)) 
+      if (is_global(m))
         init_top(m, (mchunkptr)tbase, tsize - TOP_FOOT_SIZE);
       else {
         /* Offset top by embedded malloc_state */
@@ -3778,7 +3778,7 @@
     }
 
     /* Unmap any unused mmapped segments */
-    if (HAVE_MMAP) 
+    if (HAVE_MMAP)
       released += release_unused_segments(m);
 
     /* On failure, disable autotrim to avoid repeated failed future calls */
@@ -3986,7 +3986,7 @@
     while (a < alignment) a <<= 1;
     alignment = a;
   }
-  
+
   if (bytes >= MAX_REQUEST - alignment) {
     if (m != 0)  { /* Test isn't needed but avoids compiler warning */
       MALLOC_FAILURE_ACTION;
@@ -5446,5 +5446,5 @@
     Trial version Fri Aug 28 13:14:29 1992  Doug Lea  (dl at g.oswego.edu)
       * Based loosely on libg++-1.2X malloc. (It retains some of the overall
          structure of old version,  but most details differ.)
- 
+
 */