pkg-cmake: use $(HOST_DIR) instead of $(HOST_DIR)/usr as prefix

Remove the redundant usr/ component of the HOST_DIR paths. Since a
previous commit added a symlink from $(HOST_DIR)/usr to $(HOST_DIR),
everything keeps on working.

Build-tested with a bunch of cmake packages.

Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>
Reviewed-by: Romain Naour <romain.naour@smile.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/pkg-cmake.mk

@@ -115,7 +115,7 @@ define $(2)_CONFIGURE_CMDS
 		-DCMAKE_FIND_ROOT_PATH_MODE_PROGRAM="BOTH" \
 		-DCMAKE_FIND_ROOT_PATH_MODE_LIBRARY="BOTH" \
 		-DCMAKE_FIND_ROOT_PATH_MODE_INCLUDE="BOTH" \
-		-DCMAKE_INSTALL_PREFIX="$$(HOST_DIR)/usr" \
+		-DCMAKE_INSTALL_PREFIX="$$(HOST_DIR)" \
 		-DCMAKE_C_FLAGS="$$(HOST_CFLAGS)" \
 		-DCMAKE_CXX_FLAGS="$$(HOST_CXXFLAGS)" \
 		-DCMAKE_EXE_LINKER_FLAGS="$$(HOST_LDFLAGS)" \