Cleanup code using forward declarations.

Use misc methods of avoiding unnecesary header includes.
Replace int typedefs with int##_t from stdint.h.
Replace PRI64[xdu] with PRI[xdu]64 from inttypes.h.
Normalize QT_VERSION ifs where possible.
Resolve some indirect dependencies as direct ones.
Remove extern declarations from .cpp files.

src/test/bignum_tests.cpp

@@ -1,8 +1,9 @@
-#include <boost/test/unit_test.hpp>
-#include <limits>
-
 #include "bignum.h"
-#include "util.h"
+
+#include <limits>
+#include <stdint.h>
+
+#include <boost/test/unit_test.hpp>
 
 BOOST_AUTO_TEST_SUITE(bignum_tests)
 
@@ -46,7 +47,7 @@ BOOST_AUTO_TEST_SUITE(bignum_tests)
 // Let's force this code not to be inlined, in order to actually
 // test a generic version of the function. This increases the chance
 // that -ftrapv will detect overflows.
-NOINLINE void mysetint64(CBigNum& num, int64 n)
+NOINLINE void mysetint64(CBigNum& num, int64_t n)
 {
     num.setint64(n);
 }
@@ -55,7 +56,7 @@ NOINLINE void mysetint64(CBigNum& num, int64 n)
 // value to 0, then the second one with a non-inlined function.
 BOOST_AUTO_TEST_CASE(bignum_setint64)
 {
-    int64 n;
+    int64_t n;
 
     {
         n = 0;
@@ -103,7 +104,7 @@ BOOST_AUTO_TEST_CASE(bignum_setint64)
         BOOST_CHECK(num.ToString() == "-5");
     }
     {
-        n = std::numeric_limits<int64>::min();
+        n = std::numeric_limits<int64_t>::min();
         CBigNum num(n);
         BOOST_CHECK(num.ToString() == "-9223372036854775808");
         num.setulong(0);
@@ -112,7 +113,7 @@ BOOST_AUTO_TEST_CASE(bignum_setint64)
         BOOST_CHECK(num.ToString() == "-9223372036854775808");
     }
     {
-        n = std::numeric_limits<int64>::max();
+        n = std::numeric_limits<int64_t>::max();
         CBigNum num(n);
         BOOST_CHECK(num.ToString() == "9223372036854775807");
         num.setulong(0);