[PATCH v5] build: move variable definition to top level

[Andrius Sirvys <andrius.sirvys@intel.com>]

If for debugging we disable the driver directory in the meson.build file,
we get an error because the variable "driver_classes" does not exist.
This is because driver_classes is only defined in the
drivers/meson.build file. Defining driver_classes in dpdk/meson.build file
will make it easier for compiling separate directories.

In the process, we rename driver_classes to dpdk_driver_classes for
consistency with the other variables.

Signed-off-by: Andrius Sirvys <andrius.sirvys@intel.com>
Acked-by: Bruce Richardson <bruce.richardson@intel.com>
---
v5: Rebased off of master branch
---
 drivers/meson.build | 4 ++--
 meson.build         | 3 ++-
 2 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/meson.build b/drivers/meson.build
index 69d0556d3..8c76a5659 100644
--- a/drivers/meson.build
+++ b/drivers/meson.build
@@ -2,7 +2,7 @@
 # Copyright(c) 2017 Intel Corporation
 
 # Defines the order in which the drivers are buit.
-driver_classes = ['common',
+dpdk_driver_classes = ['common',
 	       'bus',
 	       'mempool', # depends on common and bus.
 	       'net',     # depends on common, bus and mempool.
@@ -20,7 +20,7 @@ endif
 # specify -D_GNU_SOURCE unconditionally
 default_cflags += '-D_GNU_SOURCE'
 
-foreach class:driver_classes
+foreach class:dpdk_driver_classes
 	drivers = []
 	std_deps = []
 	config_flag_fmt = '' # format string used to set the value in dpdk_conf
diff --git a/meson.build b/meson.build
index 69833de82..e945a27c3 100644
--- a/meson.build
+++ b/meson.build
@@ -13,6 +13,7 @@ cc = meson.get_compiler('c')
 dpdk_conf = configuration_data()
 dpdk_libraries = []
 dpdk_static_libraries = []
+dpdk_driver_classes = []
 dpdk_drivers = []
 dpdk_extra_ldflags = []
 dpdk_app_link_libraries = []
@@ -105,7 +106,7 @@ endforeach
 message(output_message + '\n')
 
 output_message = '\n===============\nDrivers Enabled\n===============\n'
-foreach class:driver_classes
+foreach class:dpdk_driver_classes
 	class_drivers = get_variable(class + '_drivers')
 	output_message += '\n' + class + ':\n\t'
 	output_count = 0
-- 
2.17.1