Introduce PROTOBUF_INCLUDE_PATH

This avoids having to install all dependencies into the same folder
Default set so existing behavior is not changed

.bazelrc

@@ -296,9 +296,11 @@ build:windows --host_copt=/D_USE_MATH_DEFINES
 build:linux --define=PREFIX=/usr
 build:linux --define=LIBDIR=$(PREFIX)/lib
 build:linux --define=INCLUDEDIR=$(PREFIX)/include
+build:linux --define=PROTOBUF_INCLUDE_PATH=$(PREFIX)/include
 build:macos --define=PREFIX=/usr
 build:macos --define=LIBDIR=$(PREFIX)/lib
 build:macos --define=INCLUDEDIR=$(PREFIX)/include
+build:macos --define=PROTOBUF_INCLUDE_PATH=$(PREFIX)/include
 # TF_SYSTEM_LIBS do not work on windows.
 
 # By default, build TF in C++ 14 mode.

configure.py

@@ -1163,12 +1163,9 @@ def set_system_libs_flag(environ_cp):
       syslibs = ','.join(sorted(syslibs.split()))
     write_action_env_to_bazelrc('TF_SYSTEM_LIBS', syslibs)
 
-  if 'PREFIX' in environ_cp:
-    write_to_bazelrc('build --define=PREFIX=%s' % environ_cp['PREFIX'])
-  if 'LIBDIR' in environ_cp:
-    write_to_bazelrc('build --define=LIBDIR=%s' % environ_cp['LIBDIR'])
-  if 'INCLUDEDIR' in environ_cp:
-    write_to_bazelrc('build --define=INCLUDEDIR=%s' % environ_cp['INCLUDEDIR'])
+  for varname in ('PREFIX', 'LIBDIR', 'INCLUDEDIR', 'PROTOBUF_INCLUDE_PATH'):
+    if varname in environ_cp:
+      write_to_bazelrc('build --define=%s=%s' % (varname, environ_cp[varname]))
 
 
 def is_reduced_optimize_huge_functions_available(environ_cp):

third_party/systemlibs/protobuf.BUILD

@@ -38,7 +38,7 @@ genrule(
       for i in $(OUTS); do
         f=$${i#$(@D)/}
         mkdir -p $(@D)/$${f%/*}
-        ln -sf $(INCLUDEDIR)/$$f $(@D)/$$f
+        ln -sf $(PROTOBUF_INCLUDE_PATH)/$$f $(@D)/$$f
       done
     """,
 )