Allow compiling and using as DLL in windows (#502)

* printf.h fixed to compile clean - need to check whether this is the right
thing to do

* fix warnings and errors in test compiles with BUILD_SHARED_LIBS

* did requested changes and added one change to allow all tests to succeed
in windows DLL

test/format-impl-test.cc

@@ -26,6 +26,7 @@
  */
 
 #define FMT_NOEXCEPT
+#undef FMT_SHARED
 #include "test-assert.h"
 
 // Include *.cc instead of *.h to test implementation-specific stuff.

test/format-test.cc

@@ -1556,8 +1556,8 @@ TEST(FormatTest, JoinArg) {
   using fmt::join;
   int v1[3] = { 1, 2, 3 };
   std::vector<float> v2;
-  v2.push_back(1.2);
-  v2.push_back(3.4);
+  v2.push_back(1.2f);
+  v2.push_back(3.4f);
 
   EXPECT_EQ("(1, 2, 3)", format("({})", join(v1 + 0, v1 + 3, ", ")));
   EXPECT_EQ("(1)", format("({})", join(v1 + 0, v1 + 1, ", ")));

test/time-test.cc

@@ -6,6 +6,9 @@
 
  For the license information refer to format.h.
  */
+#ifdef WIN32
+#define _CRT_SECURE_NO_WARNINGS
+#endif
 
 #include "gmock/gmock.h"
 #include "fmt/time.h"