scripts: consolidate code to find bitbake path

Several of these scripts were using duplicated code (and slightly
different methods) to find the path to bitbake and add its lib
subdirectory to the Python import path. Add some common code to do this
and change the scripts to use it.

Fixes [YOCTO #5076].

(From OE-Core rev: 0b5e94e168819134dcda0433c8ae893df4ab13ce)

Signed-off-by: Paul Eggleton <paul.eggleton@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/buildhistory-diff

@@ -50,24 +50,20 @@ def main():
         parser.print_help()
         sys.exit(1)
 
-    # Set path to OE lib dir so we can import the buildhistory_analysis module
-    basepath = os.path.abspath(os.path.dirname(os.path.abspath(sys.argv[0])) + '/..')
-    newpath = basepath + '/meta/lib'
-    # Set path to bitbake lib dir so the buildhistory_analysis module can load bb.utils
-    if os.path.exists(basepath + '/bitbake/lib/bb'):
-        bitbakepath = basepath + '/bitbake'
-    else:
-        # look for bitbake/bin dir in PATH
-        bitbakepath = None
-        for pth in os.environ['PATH'].split(':'):
-            if os.path.exists(os.path.join(pth, '../lib/bb')):
-                bitbakepath = os.path.abspath(os.path.join(pth, '..'))
-                break
-        if not bitbakepath:
-            sys.stderr.write("Unable to find bitbake by searching parent directory of this script or PATH\n")
-            sys.exit(1)
+    scripts_path = os.path.abspath(os.path.dirname(os.path.abspath(sys.argv[0])))
+    lib_path = scripts_path + '/lib'
+    sys.path = sys.path + [lib_path]
+
+    import scriptpath
+
+    # Set path to OE lib dir so we can import the buildhistory_analysis module
+    scriptpath.add_oe_lib_path()
+    # Set path to bitbake lib dir so the buildhistory_analysis module can load bb.utils
+    bitbakepath = scriptpath.add_bitbake_lib_path()
+    if not bitbakepath:
+        sys.stderr.write("Unable to find bitbake by searching parent directory of this script or PATH\n")
+        sys.exit(1)
 
-    sys.path[0:0] = [newpath, bitbakepath + '/lib']
     import oe.buildhistory_analysis
 
     fromrev = 'build-minus-1'