pw_log: Remove unused macro PW_MODULE_LOG_NAME_DEFINED

PW_MODULE_LOG_NAME_DEFINED is problematic because PW_LOG_MODULE_NAME can
be overridden after the default is defined. It also behaves unexpectedly
if PW_LOG_MODULE_NAME is manually set to "".

Change-Id: I4e047bad3b7c6735e29e03896cedcb3c38f63877
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/238554
Presubmit-Verified: CQ Bot Account <[email protected]>
Reviewed-by: Taylor Cramer <[email protected]>
Pigweed-Auto-Submit: Wyatt Hepler <[email protected]>
Lint: Lint 🤖 <[email protected]>
Commit-Queue: Wyatt Hepler <[email protected]>

pw_log/docs.rst

@@ -247,9 +247,7 @@ source files, not headers. For example:
 .. c:macro:: PW_LOG_MODULE_NAME
 
    A string literal module name to use in logs. Log backends may attach this
-   name to log messages or use it for runtime filtering. Defaults to ``""``. The
-   ``PW_LOG_MODULE_NAME_DEFINED`` macro is set to ``1`` or ``0`` to indicate
-   whether ``PW_LOG_MODULE_NAME`` was overridden.
+   name to log messages or use it for runtime filtering. Defaults to ``""``.
 
 .. c:macro:: PW_LOG_FLAGS
 

pw_log/public/pw_log/options.h

@@ -38,16 +38,9 @@
 
 // Default: Module name
 //
-// An empty string is used for the module name if it is not set. The
-// PW_LOG_MODULE_NAME_DEFINED macro is set to 1 or 0 to allow pw_log backends to
-// behave differently if the module name is defined. For example, a backend
-// might prefix the format string with PW_LOG_MODULE_NAME ": ", but only if the
-// module name is provided.
-#ifdef PW_LOG_MODULE_NAME
-#define PW_LOG_MODULE_NAME_DEFINED 1
-#else
+// An empty string is used for the module name if it is not set.
+#ifndef PW_LOG_MODULE_NAME
 #define PW_LOG_MODULE_NAME ""
-#define PW_LOG_MODULE_NAME_DEFINED 0
 #endif  // PW_LOG_MODULE_NAME
 
 // Default: Log level filtering