Support OCI_LIB_DIR and OCI_INC_DIR on Windows

Author: Christopher Jones

INSTALL.md

@@ -510,6 +510,13 @@ set OCI_INC_DIR=C:\instantclient_12_1\sdk\include
 set OCI_LIB_DIR=C:\instantclient_12_1\sdk\lib\msvc
 ```
 
+If you are installing with a local database, try:
+
+```
+OCI_INC_DIR=C:\oracle\product\12.1.0\dbhome_1\oci\include
+OCI_LIB_DIR=C:\oracle\product\12.1.0\dbhome_1\oci\lib\msvc
+```
+
 Run the installer:
 
 ```

binding.gyp

@@ -67,8 +67,8 @@
     ],
     ["OS=='win'", {
       "variables" : {
-        "oci_inc_dir%" : "C:/instantclient/sdk/include",
-        "oci_lib_dir%" : "C:/instantclient/sdk/lib/msvc",
+        "oci_lib_dir%": "<!(IF DEFINED OCI_LIB_DIR (echo %OCI_LIB_DIR%) ELSE (echo C:\oracle\instantclient\sdk\lib\msvc))", 
+        "oci_inc_dir%": "<!(IF DEFINED OCI_INC_DIR (echo %OCI_INC_DIR%) ELSE (echo C:\oracle\instantclient\sdk\include))", 
       },
       "configurations" : {
         "Release" : {