Add use-libpldm-subproject option to meson.build

Allow controlling whether libpldm is sourced from
subprojects/libpldm.wrap or system/recipe dependency (recipe-sysroot).
Defaults to true so unit test always use libpldm.wrap, while Bitbake set
-Duse-libpldm-subproject=false to use the recipe-sysroot libpldm.

Change-Id: I8887cf82130064e2864dfbc16d561219b5a479cb
Signed-off-by: Muhammad Usama <muhammadusama@google.com>

meson.build

diff --git a/meson.build b/meson.build
index 58d6a05..678802e 100644
--- a/meson.build
+++ b/meson.build
@@ -128,7 +128,11 @@
     endif
 endif
 
-libpldm_dep = subproject('libpldm').get_variable('libpldm_dep')
+if get_option('use-libpldm-subproject')
+    libpldm_dep = subproject('libpldm').get_variable('libpldm_dep')
+else
+    libpldm_dep = dependency('libpldm', fallback: ['libpldm', 'libpldm_dep'])
+endif
 libbej_dep = dependency('libbej', fallback:['libbej'])
 
 libpldmutils_headers = ['.']

meson.options

diff --git a/meson.options b/meson.options
index 411d311..9413475 100644
--- a/meson.options
+++ b/meson.options
@@ -181,3 +181,11 @@
     description: '''Enable expand query option feature on redfish queries for
                     rde devices. Disabled by default'''
 )
+
+option(
+    'use-libpldm-subproject',
+    type: 'boolean',
+    value: true,
+    description: 'Force using libpldm subproject wrap instead of system dependency'
+)
+