Fix Windows compilation in image_publisher.cpp (#1061)

PR #985 added some
code that used `M_PI`, but `M_PI` is not defined in any standard, and
before including `cmath` or `math.h` in Windows it is necessary to
define `_USE_MATH_DEFINES` to ensure that `M_PI` is defined.

image_publisher/src/image_publisher.cpp

@@ -31,6 +31,10 @@
 // ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 // POSSIBILITY OF SUCH DAMAGE.
 
+// This define is added to support M_PI on Windows
+#ifndef _USE_MATH_DEFINES
+#define _USE_MATH_DEFINES
+#endif
 #include <cmath>
 #include <chrono>
 #include <limits>