Exclude routines from fortification

Since the _FORTIFY_SOURCE feature uses some routines of Glibc, they need to
be excluded from the fortification.

On top of that:
 - some tests explicitly verify that some level of fortification works
   appropriately, we therefore shouldn't modify the level set for them.
 - some objects need to be build with optimization disabled, which
   prevents _FORTIFY_SOURCE to be used for them.

Assembler files that implement architecture specific versions of the
fortified routines were not excluded from _FORTIFY_SOURCE as there is no
C header included that would impact their behavior.

Reviewed-by: Siddhesh Poyarekar <siddhesh@sourceware.org>

string/Makefile

@@ -118,6 +118,23 @@ routines := \
   xpg-strerror \
 # routines
 
+# Exclude fortified routines from being built with _FORTIFY_SOURCE
+routines_no_fortify += \
+  explicit_bzero \
+  memcpy \
+  memmove \
+  mempcpy \
+  memset \
+  stpcpy \
+  stpncpy \
+  strcat \
+  strcpy \
+  strlcat \
+  strlcpy \
+  strncat \
+  strncpy \
+  # routines_no_fortify
+
 tests := \
   bug-envz1 \
   bug-strcoll1 \