Fix namespace pollution on Windows (#117)

As described in
#116, the `io.h`
file in this project conflicts with `io.h` of windows.

This fixes that (in the somewhat narrow compilation path that i'm
exercising) by removing `include/substrait/common` from the include
path, and instead relying on the (already existing) full include-path
namespacing instead of relative includes of `io.h`.

CMakeLists.txt

@@ -29,6 +29,8 @@ option(
   "Enable substrait-cpp tests. This will enable all other build options automatically."
   ON)
 
+set(SUBSTRAIT_CPP_INCLUDE_DIR ${CMAKE_CURRENT_SOURCE_DIR}/include)
+
 # Local files come first.
 include_directories(include)
 include_directories(src)

src/substrait/common/CMakeLists.txt

@@ -19,10 +19,8 @@ add_dependencies(
   absl::status
   absl::statusor)
 target_include_directories(
-  substrait_io
-  INTERFACE
-    $<BUILD_INTERFACE:${CMAKE_CURRENT_SOURCE_DIR}/../../../include/substrait/common>
-    $<INSTALL_INTERFACE:include/substrait/common>)
+  substrait_io INTERFACE $<BUILD_INTERFACE:${SUBSTRAIT_CPP_INCLUDE_DIR}>
+                         $<INSTALL_INTERFACE:include>)
 target_link_libraries(substrait_io substrait_proto substrait_textplan_converter
                       substrait_textplan_loader absl::status absl::statusor)