binfmt/libelf, libs/libc/modlib: Optimize elf load speed: (1) Don't zero out memory, (2) Reduce the initial buffer size to 32 bytes.

libs/libc/modlib/Kconfig

@@ -33,12 +33,12 @@ config MODLIB_ALIGN_LOG2
 
 config MODLIB_BUFFERSIZE
 	int "Module I/O Buffer Size"
-	default 128
+	default 32
 	---help---
 		This is an I/O buffer that is used to access the module file.
 		Variable length items will need to be read (such as symbol names).
 		This is really just this initial size of the buffer; it will be
-		reallocated as necessary to hold large symbol names).  Default: 128
+		reallocated as necessary to hold large symbol names).  Default: 32
 
 config MODLIB_BUFFERINCR
 	int "Module I/O Buffer Realloc Increment"

libs/libc/modlib/modlib_load.c

@@ -261,7 +261,7 @@ int modlib_load(FAR struct mod_loadinfo_s *loadinfo)
 
   /* Allocate memory to hold the ELF image */
 
-  loadinfo->textalloc = (uintptr_t)lib_zalloc(loadinfo->textsize + loadinfo->datasize);
+  loadinfo->textalloc = (uintptr_t)lib_malloc(loadinfo->textsize + loadinfo->datasize);
   if (!loadinfo->textalloc)
     {
       berr("ERROR: Failed to allocate memory for the module\n");

libs/libc/modlib/modlib_symbols.c

@@ -52,12 +52,6 @@
  * Pre-processor Definitions
  ****************************************************************************/
 
-/* Amount to reallocate buffer when buffer is full */
-
-#ifndef CONFIG_MODLIB_BUFFERINCR
-#  define CONFIG_MODLIB_BUFFERINCR 32
-#endif
-
 /* Return values search for exported modules */
 
 #define SYM_NOT_FOUND 0