[PATCH] build: error out when missing elftools python module

[Bruce Richardson <bruce.richardson@intel.com>]

In the case where we use the meson python "find_installation()" function
to get our python binary, we can fail the configure/setup step if the
elftools module is missing. This avoids later errors on build when the
module is missed.

Old output (error logged and config continues):

  Program python3 (elftools) found: NO

New output:
  Program python3 found: YES (/usr/bin/python3)
  Program python3 (elftools) found: NO

  ../buildtools/meson.build:15:31: ERROR: python3 is missing modules: elftools

Signed-off-by: Bruce Richardson <bruce.richardson@intel.com>
---
 buildtools/meson.build | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/buildtools/meson.build b/buildtools/meson.build
index 7b5e449cdb..12abbdff9c 100644
--- a/buildtools/meson.build
+++ b/buildtools/meson.build
@@ -9,8 +9,11 @@ python3_required_modules = []
 if host_machine.system() != 'windows'
     python3_required_modules = ['elftools']
 endif
-python3 = import('python').find_installation('python3', required: false, modules: python3_required_modules)
+python3 = import('python').find_installation('python3', required: false)
 if python3.found()
+    # If python3 is found, check that we have pyelftools installed.
+    python3 = import('python').find_installation('python3', required: true,
+            modules: python3_required_modules)
     py3 = [python3]
 else
     py3 = ['meson', 'runpython']
-- 
2.48.1