fix: error: -Werror=misleading-indentation

Compilation of bitmonero on Arch with gcc 6.1 results in the following
error:

/home/mwo/bitmonero/tests/unit_tests/hardfork.cpp: In member function ‘virtual void TestDB::set_hard_fork_version(uint64_t, uint8_t)’:
/home/mwo/bitmonero/tests/unit_tests/hardfork.cpp:132:5: error: this ‘if’ clause does not guard... [-Werror=misleading-indentation]
     if (versions.size() <= height) versions.resize(height+1); versions[height] = version;

This can be fixed by simply unfolding this line into three lines.

tests/unit_tests/hardfork.cpp

@@ -129,7 +129,9 @@ public:
     return starting_height[version];
   }
   virtual void set_hard_fork_version(uint64_t height, uint8_t version) {
-    if (versions.size() <= height) versions.resize(height+1); versions[height] = version;
+    if (versions.size() <= height) 
+      versions.resize(height+1); 
+    versions[height] = version;
   }
   virtual uint8_t get_hard_fork_version(uint64_t height) const {
     return versions[height];