Inline TagAlias constructor

It is trivial enough that the function call is not worth it, and
lets us remove one TU from compilation.

src/CMakeLists.txt

@@ -175,7 +175,6 @@ set(IMPL_SOURCES
     ${SOURCES_DIR}/internal/catch_stream.cpp
     ${SOURCES_DIR}/internal/catch_stringref.cpp
     ${SOURCES_DIR}/internal/catch_string_manip.cpp
-    ${SOURCES_DIR}/catch_tag_alias.cpp
     ${SOURCES_DIR}/catch_tag_alias_autoregistrar.cpp
     ${SOURCES_DIR}/internal/catch_tag_alias_registry.cpp
     ${SOURCES_DIR}/catch_test_case_info.cpp

src/catch2/catch_tag_alias.cpp

@@ -1,5 +0,0 @@
-#include <catch2/catch_tag_alias.hpp>
-
-namespace Catch {
-    TagAlias::TagAlias(std::string const & _tag, SourceLineInfo _lineInfo): tag(_tag), lineInfo(_lineInfo) {}    
-}

src/catch2/catch_tag_alias.hpp

@@ -15,7 +15,10 @@
 namespace Catch {
 
     struct TagAlias {
-        TagAlias(std::string const& _tag, SourceLineInfo _lineInfo);
+        TagAlias(std::string const& _tag, SourceLineInfo _lineInfo):
+            tag(_tag),
+            lineInfo(_lineInfo)
+        {}
 
         std::string tag;
         SourceLineInfo lineInfo;