openvc: disable precompiled headers

this commit fixes musl build

precompiled headers are not strictly necessary according to
https://gcc.gnu.org/onlinedocs/gcc/Precompiled-Headers.html

precompiled headers will probably be broken anyway in cross-compile cases

Signed-off-by: Dirk Neukirchen <dirkneukirchen@web.de>

libs/opencv/Makefile

@@ -52,6 +52,8 @@ CMAKE_OPTIONS += -DBUILD_opencv_gpu:BOOL=OFF \
 	-DWITH_LIBV4L:BOOL=OFF \
 	-DWITH_PNG:BOOL=OFF \
 	-DWITH_TIFF:BOOL=OFF \
+	-DCMAKE_VERBOSE:BOOL=OFF \
+	-DENABLE_PRECOMPILED_HEADERS=OFF
 
 define Build/InstallDev
 	$(INSTALL_DIR) $(1)/usr/include