Support external (i.e. user-defined) trace annotations (#195)

* Support external (i.e. user-defined) trace annotations

- tweaked the python examples to be more balanced
- updated the user-api example to conform to user API changes
- moved the get/set for State and ThreadState to state.{hpp,cpp}
- introduced user-provided trace annotations
- added perfetto python category
- moved coverage impl files around
- created enumerations for mapping category enums to category types
- created enumerations for mapping annotation type enums to annotation values
- moved tracing::add_perfetto_annotations to tracing/annotation.hpp
- utility make_index_sequence_range
- libomnitrace-dl: omnitrace_push_category_region
- libomnitrace-dl: omnitrace_pop_category_region
- libomnitrace-user: omnitrace_user_push_annotated_region
- libomnitrace-user: omnitrace_user_pop_annotated_region
- libpyomnitrace: support extra annotations via annotate_trace config value
  - filename
  - line
  - last attempted instr in bytecode (lasti)
  - argcount
  - num local variables
  - stacksize
- omnitrace-python: -a / --annotate-traces option

* tweak ubuntu-focal workflow

* Fix installation of omnitrace-user headers

* ubuntu-focal-codecov workflow update

- Install texinfo

* Update timemory submodule

examples/user-api/user-api.cpp

@@ -1,10 +1,14 @@
 
+#include "omnitrace/categories.h"
+#include "omnitrace/types.h"
 #include <omnitrace/user.h>
 
 #include <atomic>
 #include <cassert>
+#include <cerrno>
 #include <cstdio>
 #include <cstdlib>
+#include <cstring>
 #include <sstream>
 #include <thread>
 #include <vector>
@@ -22,19 +26,16 @@ custom_push_region(const char* name);
 
 namespace
 {
-int (*omnitrace_push_region_f)(const char*) = nullptr;
-}
+omnitrace_user_callbacks_t custom_callbacks   = OMNITRACE_USER_CALLBACKS_INIT;
+omnitrace_user_callbacks_t original_callbacks = OMNITRACE_USER_CALLBACKS_INIT;
+}  // namespace
 
 int
 main(int argc, char** argv)
 {
-    // get the internal callback to start a user-defined region
-    omnitrace_user_get_callbacks(OMNITRACE_USER_REGION, (void**) &omnitrace_push_region_f,
-                                 nullptr);
-    // assign the custom callback to start a user-defined region
-    if(omnitrace_push_region_f)
-        omnitrace_user_configure(OMNITRACE_USER_REGION, (void*) &custom_push_region,
-                                 nullptr);
+    custom_callbacks.push_region = &custom_push_region;
+    omnitrace_user_configure(OMNITRACE_USER_UNION_CONFIG, custom_callbacks,
+                             &original_callbacks);
 
     omnitrace_user_push_region(argv[0]);
     omnitrace_user_push_region("initialization");
@@ -100,6 +101,26 @@ run(size_t nitr, long n)
 int
 custom_push_region(const char* name)
 {
+    if(!original_callbacks.push_region || !original_callbacks.push_annotated_region)
+        return OMNITRACE_USER_ERROR_NO_BINDING;
+
     printf("Pushing custom region :: %s\n", name);
-    return (*omnitrace_push_region_f)(name);
+
+    if(original_callbacks.push_annotated_region)
+    {
+        int32_t _err = errno;
+        char*   _msg = nullptr;
+        char    _buff[1024];
+        if(_err != 0) _msg = strerror_r(_err, _buff, sizeof(_buff));
+
+        omnitrace_annotation_t _annotations[] = {
+            { "errno", OMNITRACE_INT32, &_err }, { "strerror", OMNITRACE_STRING, _msg }
+        };
+
+        errno = 0;  // reset errno
+        return (*original_callbacks.push_annotated_region)(
+            name, _annotations, sizeof(_annotations) / sizeof(omnitrace_annotation_t));
+    }
+
+    return (*original_callbacks.push_region)(name);
 }