ldso:sh: fix compiler warning due to unused-but-set-variable

gcc 4.6.x raises useful warnings due to unused-but-set-variable,
This patch fixes the following one by using properly preprocessor
guard

In file included from ldso/libdl/libdl.c:129:0:
./ldso/ldso/sh/elfinterp.c: In function '_dl_do_reloc':
./ldso/ldso/sh/elfinterp.c:163:22: warning: variable 'tls_tpnt' set but not used [-Wunused-but-set-variable]

Signed-off-by: Carmelo Amoroso <carmelo.amoroso@st.com>

ldso/ldso/sh/elfinterp.c

@@ -160,7 +160,9 @@ _dl_do_reloc (struct elf_resolve *tpnt, struct r_scope_elem *scope,
 	unsigned long old_val;
 #endif
 
+#if defined USE_TLS && USE_TLS
 	struct elf_resolve *tls_tpnt = NULL;
+#endif
 	struct symbol_ref sym_ref;
 
 	reloc_addr = (unsigned long *)(intptr_t) (tpnt->loadaddr + (unsigned long) rpnt->r_offset);
@@ -193,7 +195,9 @@ _dl_do_reloc (struct elf_resolve *tpnt, struct r_scope_elem *scope,
 			_dl_debug_lookup (symname, tpnt, &symtab[symtab_index],
 							&sym_ref, elf_machine_type_class(reloc_type));
 		}
+#if defined USE_TLS && USE_TLS
 		tls_tpnt = sym_ref.tpnt;
+#endif
 	}
 
 #if defined (__SUPPORT_LD_DEBUG__)