meson: update deprecated source_root()

The `source_root` function has been split into `project_source_root`
and `global_source_root` variants as of meson-0.57.  Update to use
`project_source_root`, which is generally the appropriate variant to
use.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I32b2a66a742c9b0a78e9fb93276d62aff42ab240
diff --git a/meson.build b/meson.build
index 03ee7fb..0e53730 100644
--- a/meson.build
+++ b/meson.build
@@ -141,7 +141,7 @@
 subdir('xyz/openbmc_project/Dump/Internal/Create')
 
 python = find_program('python3')
-errors_map_gen_file_loc = meson.source_root()
+errors_map_gen_file_loc = meson.project_source_root()
 errors_map_gen_file_loc += '/errors_map_gen.py'
 
 errors_map_hpp = custom_target(
diff --git a/xyz/openbmc_project/Dump/Internal/Create/meson.build b/xyz/openbmc_project/Dump/Internal/Create/meson.build
index fd25ad9..a34e7c3 100644
--- a/xyz/openbmc_project/Dump/Internal/Create/meson.build
+++ b/xyz/openbmc_project/Dump/Internal/Create/meson.build
@@ -3,7 +3,7 @@
 server_hpp = custom_target(
                 'server.hpp',
                 command : [
-                    sdbusplusplus_prog, '-r', meson.source_root(),
+                    sdbusplusplus_prog, '-r', meson.project_source_root(),
                     'interface',
                     'server-header',
                     'xyz.openbmc_project.Dump.Internal.Create',
@@ -18,7 +18,7 @@
 server_cpp = custom_target(
                 'server.cpp',
                 command : [
-                    sdbusplusplus_prog, '-r', meson.source_root(),
+                    sdbusplusplus_prog, '-r', meson.project_source_root(),
                     'interface',
                     'server-cpp',
                     'xyz.openbmc_project.Dump.Internal.Create'