util: Use g_new() & friends where that makes obvious sense

g_new(T, n) is neater than g_malloc(sizeof(T) * n).  It's also safer,
for two reasons.  One, it catches multiplication overflowing size_t.
Two, it returns T * rather than void *, which lets the compiler catch
more type errors.

This commit only touches allocations with size arguments of the form
sizeof(T).

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

util/hbitmap.c

diff --git a/util/hbitmap.c b/util/hbitmap.c
index b3060e6..ab13971 100644
--- a/util/hbitmap.c
+++ b/util/hbitmap.c
@@ -373,7 +373,7 @@
 
 HBitmap *hbitmap_alloc(uint64_t size, int granularity)
 {
-    HBitmap *hb = g_malloc0(sizeof (struct HBitmap));
+    HBitmap *hb = g_new0(struct HBitmap, 1);
     unsigned i;
 
     assert(granularity >= 0 && granularity < 64);
@@ -384,7 +384,7 @@
     hb->granularity = granularity;
     for (i = HBITMAP_LEVELS; i-- > 0; ) {
         size = MAX((size + BITS_PER_LONG - 1) >> BITS_PER_LEVEL, 1);
-        hb->levels[i] = g_malloc0(size * sizeof(unsigned long));
+        hb->levels[i] = g_new0(unsigned long, size);
     }
 
     /* We necessarily have free bits in level 0 due to the definition

util/iov.c

diff --git a/util/iov.c b/util/iov.c
index 24566c8..2fb18e6 100644
--- a/util/iov.c
+++ b/util/iov.c
@@ -253,7 +253,7 @@
 
 void qemu_iovec_init(QEMUIOVector *qiov, int alloc_hint)
 {
-    qiov->iov = g_malloc(alloc_hint * sizeof(struct iovec));
+    qiov->iov = g_new(struct iovec, alloc_hint);
     qiov->niov = 0;
     qiov->nalloc = alloc_hint;
     qiov->size = 0;
@@ -277,7 +277,7 @@
 
     if (qiov->niov == qiov->nalloc) {
         qiov->nalloc = 2 * qiov->nalloc + 1;
-        qiov->iov = g_realloc(qiov->iov, qiov->nalloc * sizeof(struct iovec));
+        qiov->iov = g_renew(struct iovec, qiov->iov, qiov->nalloc);
     }
     qiov->iov[qiov->niov].iov_base = base;
     qiov->iov[qiov->niov].iov_len = len;