Refactor profiling

Refactored core profiling codebase into two logical parts:

(a) `prof_data.c`: core internal data structure managing & dumping;
(b) `prof.c`: mutexes & outward-facing APIs.

Some internal functions had to be exposed out, but there are not
that many of them if the modularization is (hopefully) clean enough.

msvc/projects/vc2017/jemalloc/jemalloc.vcxproj

@@ -58,6 +58,7 @@
     <ClCompile Include="..\..\..\..\src\pages.c" />
     <ClCompile Include="..\..\..\..\src\prng.c" />
     <ClCompile Include="..\..\..\..\src\prof.c" />
+    <ClCompile Include="..\..\..\..\src\prof_data.c" />
     <ClCompile Include="..\..\..\..\src\prof_log.c" />
     <ClCompile Include="..\..\..\..\src\rtree.c" />
     <ClCompile Include="..\..\..\..\src\sc.c" />

msvc/projects/vc2017/jemalloc/jemalloc.vcxproj.filters

@@ -67,6 +67,9 @@
     <ClCompile Include="..\..\..\..\src\prof.c">
       <Filter>Source Files</Filter>
     </ClCompile>
+    <ClCompile Include="..\..\..\..\src\prof_data.c">
+      <Filter>Source Files</Filter>
+    </ClCompile>
     <ClCompile Include="..\..\..\..\src\prof_log.c">
       <Filter>Source Files</Filter>
     </ClCompile>