Use gcc warning flag -Wempty-body, fix warnings

diff --git a/configure b/configure
index 6e4917a..61626b8 100755
--- a/configure
+++ b/configure
@@ -140,7 +140,7 @@  LDFLAGS="-g $LDFLAGS"

 gcc_flags="-Wold-style-declaration -Wold-style-definition -Wtype-limits"
 gcc_flags="-Wformat-security -Wformat-y2k -Winit-self
-Wignored-qualifiers $gcc_flags"
-gcc_flags="-Wmissing-include-dirs -Wclobbered $gcc_flags"
+gcc_flags="-Wmissing-include-dirs -Wclobbered -Wempty-body $gcc_flags"
 gcc_flags="-fstack-protector-all $gcc_flags"
 cat > $TMPC << EOF
 int main(void) { return 0; }
diff --git a/hw/omap_i2c.c b/hw/omap_i2c.c
index d7c1888..d133977 100644
--- a/hw/omap_i2c.c
+++ b/hw/omap_i2c.c
@@ -190,8 +190,9 @@  static uint32_t omap_i2c_read(void *opaque,
target_phys_addr_t addr)
             if (s->rxlen > 2)
                 s->fifo >>= 16;
             s->rxlen -= 2;
-        } else
-            /* XXX: remote access (qualifier) error - what's that?  */;
+        } else {
+            /* XXX: remote access (qualifier) error - what's that?  */
+        }
         if (!s->rxlen) {
             s->stat &= ~(1 << 3);				/* RRDY */
             if (((s->control >> 10) & 1) &&			/* MST */
diff --git a/hw/omap_mmc.c b/hw/omap_mmc.c
index 15cbf06..9d167ff 100644
--- a/hw/omap_mmc.c
+++ b/hw/omap_mmc.c
@@ -559,8 +559,9 @@  static void omap_mmc_cover_cb(void *opaque, int
line, int level)
     if (!host->cdet_state && level) {
         host->status |= 0x0002;
         omap_mmc_interrupts_update(host);
-        if (host->cdet_wakeup)
-            /* TODO: Assert wake-up */;
+        if (host->cdet_wakeup) {
+            /* TODO: Assert wake-up */
+        }
     }

     if (host->cdet_state != level) {
diff --git a/hw/pxa2xx.c b/hw/pxa2xx.c
index ec7fd68..eba76cb 100644
--- a/hw/pxa2xx.c
+++ b/hw/pxa2xx.c
@@ -1877,8 +1877,9 @@  static void pxa2xx_fir_write(void *opaque,
target_phys_addr_t addr,
         s->control[0] = value;
         if (!(value & (1 << 4)))			/* RXE */
             s->rx_len = s->rx_start = 0;
-        if (!(value & (1 << 3)))			/* TXE */
-            /* Nop */;
+        if (!(value & (1 << 3))) {                      /* TXE */
+            /* Nop */
+        }
         s->enable = value & 1;				/* ITR */
         if (!s->enable)
             s->status[0] = 0;
diff --git a/hw/soc_dma.c b/hw/soc_dma.c
index e116e63..23ec516 100644
--- a/hw/soc_dma.c
+++ b/hw/soc_dma.c
@@ -192,12 +192,13 @@  static void soc_dma_ch_freq_update(struct dma_s *s)
     if (s->enabled_count)
         /* We completely ignore channel priorities and stuff */
         s->channel_freq = s->soc.freq / s->enabled_count;
-    else
+    else {
         /* TODO: Signal that we want to disable the functional clock and let
          * the platform code decide what to do with it, i.e. check that
          * auto-idle is enabled in the clock controller and if we are stopping
          * the clock, do the same with any parent clocks that had only one
-         * user keeping them on and auto-idle enabled.  */;
+         * user keeping them on and auto-idle enabled.  */
+    }
 }

 void soc_dma_set_request(struct soc_dma_ch_s *ch, int level)
diff --git a/target-cris/mmu.c b/target-cris/mmu.c
index 773438e..3f290ba 100644
--- a/target-cris/mmu.c
+++ b/target-cris/mmu.c
@@ -33,7 +33,7 @@ 
 #define D(x) x
 #define D_LOG(...) qemu_log(__VA_ARGS__)
 #else
-#define D(x)
+#define D(x) do { } while (0)
 #define D_LOG(...) do { } while (0)
 #endif