Use gmock/gtest headers when PRIVATELIB is defined

The move to /usr/include/private prefixed paths seems to require a bit more
effort in order to compile programs.

Install the headers to /usr/include/private/g{mock,test}/... and automatically
include /usr/include/private in GTESTS_CXXFLAGS to make compilation seamless. I
will work on the more global problem later with @bdrewery.

lib/googletest/gmock/Makefile

@@ -17,7 +17,7 @@ LDFLAGS+=	-L${.OBJDIR:H}/gtest
 
 INCSGROUPS=	MAIN_INCS INTERNAL_INCS INTERNAL_CUSTOM_INCS
 
-MAIN_INCSDIR=	${INCLUDEDIR}/gmock
+MAIN_INCSDIR=	${INCLUDEDIR}${PRIVATELIB:D/private/${LIB}}
 MAIN_INCS+=	gmock/gmock-matchers.h
 MAIN_INCS+=	gmock/gmock-more-actions.h
 MAIN_INCS+=	gmock/gmock-generated-actions.h
@@ -30,12 +30,12 @@ MAIN_INCS+=	gmock/gmock-spec-builders.h
 MAIN_INCS+=	gmock/gmock.h
 MAIN_INCS+=	gmock/gmock-actions.h
 
-INTERNAL_INCSDIR=	${INCLUDEDIR}/gmock/internal
+INTERNAL_INCSDIR=	${MAIN_INCSDIR}/internal
 INTERNAL_INCS+=		gmock/internal/gmock-port.h
 INTERNAL_INCS+=		gmock/internal/gmock-internal-utils.h
 INTERNAL_INCS+=		gmock/internal/gmock-generated-internal-utils.h
 
-INTERNAL_CUSTOM_INCSDIR= ${INCLUDEDIR}/gmock/internal/custom
+INTERNAL_CUSTOM_INCSDIR= ${INTERNAL_INCSDIR}/custom
 INTERNAL_CUSTOM_INCS+=	gmock/internal/custom/gmock-port.h
 INTERNAL_CUSTOM_INCS+=	gmock/internal/custom/gmock-matchers.h
 INTERNAL_CUSTOM_INCS+=	gmock/internal/custom/gmock-generated-actions.h

lib/googletest/gtest/Makefile

@@ -13,7 +13,7 @@ CXXFLAGS+=	-I${GOOGLETEST_SRCROOT}
 
 INCSGROUPS=	MAIN_INCS INTERNAL_INCS INTERNAL_CUSTOM_INCS
 
-MAIN_INCSDIR=	${INCLUDEDIR}/gtest
+MAIN_INCSDIR=	${INCLUDEDIR}${PRIVATELIB:D/private/${LIB}}
 MAIN_INCS+=	gtest/gtest-death-test.h
 MAIN_INCS+=	gtest/gtest-message.h
 MAIN_INCS+=	gtest/gtest-param-test.h
@@ -25,7 +25,7 @@ MAIN_INCS+=	gtest/gtest.h
 MAIN_INCS+=	gtest/gtest_pred_impl.h
 MAIN_INCS+=	gtest/gtest_prod.h
 
-INTERNAL_INCSDIR=	${INCLUDEDIR}/gtest/internal
+INTERNAL_INCSDIR=	${MAIN_INCSDIR}/internal
 INTERNAL_INCS+=	gtest/internal/gtest-death-test-internal.h
 INTERNAL_INCS+=	gtest/internal/gtest-filepath.h
 INTERNAL_INCS+=	gtest/internal/gtest-internal.h
@@ -38,7 +38,7 @@ INTERNAL_INCS+=	gtest/internal/gtest-string.h
 INTERNAL_INCS+=	gtest/internal/gtest-tuple.h
 INTERNAL_INCS+=	gtest/internal/gtest-type-util.h
 
-INTERNAL_CUSTOM_INCSDIR= ${INCLUDEDIR}/gtest/internal/custom
+INTERNAL_CUSTOM_INCSDIR= ${INTERNAL_INCSDIR}/custom
 INTERNAL_CUSTOM_INCS+=	gtest/internal/custom/gtest-port.h
 INTERNAL_CUSTOM_INCS+=	gtest/internal/custom/gtest-printers.h
 INTERNAL_CUSTOM_INCS+=	gtest/internal/custom/gtest.h

share/mk/googletest.test.inc.mk

@@ -7,3 +7,6 @@ GTESTS_CXXFLAGS+= -DGTESTS_HAS_STREAM_REDIRECTION=1
 GTESTS_CXXFLAGS+= -DGTESTS_LANG_CXX11=1
 GTESTS_CXXFLAGS+= -frtti
 GTESTS_CXXFLAGS+= -std=c++11
+
+# XXX: src.libnames.mk should handle adding this directory.
+GTESTS_CXXFLAGS+= -I${DESTDIR}${INCLUDEDIR}/private