Silence -Wcast-qual const qualifier warning. n-i-bz.

m_debuginfo/readmacho.c:395:30: warning: cast from 'const void *' to 'DiSym *' drops const qualifier [-Wcast-qual]
   const DiSym* s1 = (DiSym*)v1;
                             ^
m_debuginfo/readmacho.c:396:30: warning: cast from 'const void *' to 'DiSym *' drops const qualifier [-Wcast-qual]
   const DiSym* s2 = (DiSym*)v2;
                             ^
m_libcsignal.c:481:49: warning: cast from 'const vki_sigset_t *' to 'vki_sigset_t *' drops const qualifier [-Wcast-qual]
  VG_(sigintersectset)(&pending, (vki_sigset_t*)set);
                                                ^

No regressions on OS X 10.10

Before:

== 596 tests, 219 stderr failures, 10 stdout failures, 0 stderrB failures, 0 stdoutB failures, 30 post failures ==

After:

== 596 tests, 219 stderr failures, 10 stdout failures, 0 stderrB failures, 0 stdoutB failures, 30 post failures ==

git-svn-id: svn://svn.valgrind.org/valgrind/trunk@15711 a5019735-40e9-0310-863c-91ae7b9d1cf9
diff --git a/coregrind/m_debuginfo/readmacho.c b/coregrind/m_debuginfo/readmacho.c
index a471ebb..98ab048 100644
--- a/coregrind/m_debuginfo/readmacho.c
+++ b/coregrind/m_debuginfo/readmacho.c
@@ -392,8 +392,8 @@
    the primary name as a secondary sort key. */
 static Int cmp_DiSym_by_start_then_name ( const void* v1, const void* v2 )
 {
-   const DiSym* s1 = (DiSym*)v1;
-   const DiSym* s2 = (DiSym*)v2;
+   const DiSym* s1 = (const DiSym*)v1;
+   const DiSym* s2 = (const DiSym*)v2;
    if (s1->avmas.main < s2->avmas.main) return -1;
    if (s1->avmas.main > s2->avmas.main) return 1;
    return VG_(strcmp)(s1->pri_name, s2->pri_name);
diff --git a/coregrind/m_libcsignal.c b/coregrind/m_libcsignal.c
index 2cab449..557e219 100644
--- a/coregrind/m_libcsignal.c
+++ b/coregrind/m_libcsignal.c
@@ -478,7 +478,7 @@
 
   /* don't try for signals not in 'set' */
   /* pending = pending `intersect` set */
-  VG_(sigintersectset)(&pending, (vki_sigset_t*)set);
+  VG_(sigintersectset)(&pending, (const vki_sigset_t*)set);
 
   /* don't try for signals not blocked at the moment */
   ir = VG_(sigprocmask)(VKI_SIG_SETMASK, NULL, &blocked);