symtabs: improve handling of symbol lookups

When CONFIG_SYMTAB_ORDEREDBYNAME is selected most code will use
the ordered search function. When it is not selected no code will
use the ordered search function. This change merges the two
functions and varies its behaviour based on the config setting,
such that all callers can simply call the one search function
and get the best behaviour.

An additional configuration option allows leading underscores to
be stripped from symbols being relocated in loaded objects. This
allows toolchains which prefix C symbol with underscores to make
loadable ELF objects.

binfmt/Kconfig

@@ -66,12 +66,3 @@ config BINFMT_CONSTRUCTORS
 	---help---
 		Built-in support for C++ constructors in loaded modules.  Currently
 		only support for ELF binary formats.
-
-config SYMTAB_ORDEREDBYNAME
-	bool "Symbol Tables Ordered by Name"
-	default n
-	---help---
-		Select if the symbol table is ordered by symbol name.  In this case,
-		the logic can perform faster lookups using a binary search.
-		Otherwise, the symbol table is assumed to be un-ordered and only
-		slow, linear searches are supported.

binfmt/libelf/libelf_symbols.c

@@ -290,14 +290,8 @@ int elf_symvalue(FAR struct elf_loadinfo_s *loadinfo, FAR Elf_Sym *sym,
 
         /* Check if the base code exports a symbol of this name */
 
-#ifdef CONFIG_SYMTAB_ORDEREDBYNAME
-        symbol = symtab_findorderedbyname(exports,
-                                          (FAR char *)loadinfo->iobuffer,
-                                          nexports);
-#else
         symbol = symtab_findbyname(exports, (FAR char *)loadinfo->iobuffer,
                                    nexports);
-#endif
         if (!symbol)
           {
             berr("SHN_UNDEF: Exported symbol \"%s\" not found\n",

binfmt/libnxflat/libnxflat_bind.c

@@ -461,11 +461,7 @@ static inline int nxflat_bindimports(FAR struct nxflat_loadinfo_s *loadinfo,
 
           /* Find the exported symbol value for this symbol name. */
 
-#ifdef CONFIG_SYMTAB_ORDEREDBYNAME
-          symbol = symtab_findorderedbyname(exports, symname, nexports);
-#else
           symbol = symtab_findbyname(exports, symname, nexports);
-#endif
           if (!symbol)
             {
               berr("Exported symbol \"%s\" not found\n", symname);