package/webkitgtk: needs >= GCC 7

CMakeLists.txt contains a toolchain check:

if (${CMAKE_CXX_COMPILER_ID} STREQUAL "GNU")
    if (${CMAKE_CXX_COMPILER_VERSION} VERSION_LESS "7.3.0")
        message(FATAL_ERROR "GCC 7.3 or newer is required to build WebKit. Use a newer GCC version or Clang.")
    endif ()
endif ()

So bump the toolchain dependency to >= GCC 7.  The check is really about >=
7.3.0, but we do not have such detailed version checks.  Given that GCC
7.3.0 was released in January 2018 (and 7.1.0 in May 2017), most external
GCC 7.x toolchains probably use >= 7.3.0.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
(cherry picked from commit ec1ff802df9a0f17dd2b734ba536a5e206aa5aa4)
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

package/webkitgtk/Config.in

@@ -12,19 +12,19 @@ config BR2_PACKAGE_WEBKITGTK_ARCH_SUPPORTS
 	depends on BR2_TOOLCHAIN_HAS_SYNC_4
 	depends on BR2_PACKAGE_LIBGPG_ERROR_ARCH_SUPPORTS # libgcrypt
 
-comment "webkitgtk needs libgtk3 and a glibc toolchain w/ C++, gcc >= 6, host gcc >= 4.8"
+comment "webkitgtk needs libgtk3 and a glibc toolchain w/ C++, gcc >= 7, host gcc >= 4.8"
 	depends on BR2_PACKAGE_WEBKITGTK_ARCH_SUPPORTS
 	depends on !BR2_PACKAGE_LIBGTK3 || !BR2_INSTALL_LIBSTDCPP || \
 		!BR2_TOOLCHAIN_USES_GLIBC || \
 		!BR2_HOST_GCC_AT_LEAST_4_8 || \
-		!BR2_TOOLCHAIN_GCC_AT_LEAST_6
+		!BR2_TOOLCHAIN_GCC_AT_LEAST_7
 	depends on BR2_USE_MMU
 
 config BR2_PACKAGE_WEBKITGTK
 	bool "webkitgtk"
 	depends on BR2_INSTALL_LIBSTDCPP
 	depends on BR2_HOST_GCC_AT_LEAST_4_8 # icu
-	depends on BR2_TOOLCHAIN_GCC_AT_LEAST_6
+	depends on BR2_TOOLCHAIN_GCC_AT_LEAST_7
 	depends on BR2_TOOLCHAIN_USES_GLIBC
 	depends on BR2_PACKAGE_LIBGTK3
 	depends on BR2_PACKAGE_WEBKITGTK_ARCH_SUPPORTS