Add a --multiarch-triplet switch to configure

Add a --multiarch-triplet switch to configure. The switch will allow
files to be search for each default path in path/<triplet> and then
path.
Default paths handled that way:
- CONFIG_TCC_SYSINCLUDE_PATHS
- CONFIG_TCC_LIBPATH
- path to crt*.o
- path to libgcc_s.so.1

Path missing: elf interpreter path (will be handled in another commit)

tcc.h

@@ -139,37 +139,9 @@
 #define true 1
 typedef int BOOL;
 
-#ifndef CONFIG_TCC_LDDIR
-  #if defined(TCC_TARGET_X86_64_CENTOS)
-    #define CONFIG_TCC_LDDIR "/lib64"
-  #else
-    #define CONFIG_TCC_LDDIR "/lib"
-  #endif
-#endif
-
-/* path to find crt1.o, crti.o and crtn.o */
-#ifndef CONFIG_TCC_CRT_PREFIX
-# define CONFIG_TCC_CRT_PREFIX "/usr" CONFIG_TCC_LDDIR
-#endif
-
-#ifndef CONFIG_TCC_SYSINCLUDE_PATHS
-# ifdef TCC_TARGET_PE
-#  define CONFIG_TCC_SYSINCLUDE_PATHS "\b/include;\b/include/winapi"
-# else
-#  define CONFIG_TCC_SYSINCLUDE_PATHS "/usr/local/include:/usr/include:\b/include"
-# endif
-#endif
-
-#ifndef CONFIG_TCC_LIBPATH
-# ifdef TCC_TARGET_PE
-#  define CONFIG_TCC_LIBPATH "\b/lib"
-# else
-#  define CONFIG_TCC_LIBPATH \
-        CONFIG_SYSROOT CONFIG_TCC_CRT_PREFIX \
-    ":" CONFIG_SYSROOT CONFIG_TCC_LDDIR \
-    ":" CONFIG_SYSROOT "/usr/local" CONFIG_TCC_LDDIR
-# endif
-#endif
+/* See definition of default values of CONFIG_TCC_LDDIR, CONFIG_TCC_CRT_PREFIX,
+   CONFIG_TCC_SYSINCLUDE_PATHS and CONFIG_TCC_LIBPATH in config.h or configure
+ */
 
 #define INCLUDE_STACK_SIZE  32
 #define IFDEF_STACK_SIZE    64