Reduce the header declarations (#1342)

- Since we have style rules to include foo.hpp at the top of its
  corresponding foo.cpp, this takes any headers included by foo.hpp
  as being also guaranteed for foo.cpp.

- Use C-style <foo.h> instead of <cfoo>, since the latter only
  guarantees putting symbols in the `std` namespace, which we are
  not using for C functions (e.g. `printf` not `std::printf`).

- Remove now-unused `__PRETTY_FUNCTION__` reporting

src/gfx/process.cpp

@@ -4,16 +4,16 @@
 
 #include <algorithm>
 #include <assert.h>
-#include <cinttypes>
-#include <climits>
-#include <cstdio>
 #include <errno.h>
 #include <fstream>
+#include <inttypes.h>
+#include <limits.h>
 #include <memory>
 #include <optional>
 #include <png.h>
 #include <setjmp.h>
 #include <stdint.h>
+#include <stdio.h>
 #include <string.h>
 #include <tuple>
 #include <unordered_set>