bitbake: taskdata: Improve handling of regex in ASSUME_PROVIDED

ASSUME_PROVIDED can take regexs however the current way of handling
this in code is suboptimal. It means that you can add something like:

DEPENDS += "texinfo-nativejunk-that-does-not-exist"

and if texinfo-native is in ASSUME_PROVIDED, no error will occur.

Update the code to only treat something as a regex if a start or end
anchor character is present (which wouldn't be valid in a recipe name).

[YOCTO #13893]

(Bitbake rev: 3d72e23109990970fbb1086923277af752168b4a)

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

bitbake/lib/bb/taskdata.py

@@ -21,8 +21,13 @@ def re_match_strings(target, strings):
     Whether or not the string 'target' matches
     any one string of the strings which can be regular expression string
     """
-    return any(name == target or re.match(name, target)
-               for name in strings)
+    for name in strings:
+        if name.startswith("^") or name.endswith("$"):
+            if re.match(name, target):
+                return True
+        elif name == target:
+            return True
+    return False
 
 class TaskEntry:
     def __init__(self):