refactor: Remove redundant c_str() calls in formatting

Our formatter, tinyformat, *never* needs `c_str()` for strings.
Remove redundant `c_str()` calls for:

- `strprintf`
- `LogPrintf`
- `tfm::format`

1 files changed, 2 insertions, 2 deletions

diff --git a/src/sync.cpp b/src/sync.cpp
index 653800ae4e..257093fad1 100644
--- a/src/sync.cpp
+++ b/src/sync.cpp
@@ -173,7 +173,7 @@ void AssertLockHeldInternal(const char* pszName, const char* pszFile, int nLine,
     for (const std::pair<void*, CLockLocation>& i : g_lockstack)
         if (i.first == cs)
             return;
-    tfm::format(std::cerr, "Assertion failed: lock %s not held in %s:%i; locks held:\n%s", pszName, pszFile, nLine, LocksHeld().c_str());
+    tfm::format(std::cerr, "Assertion failed: lock %s not held in %s:%i; locks held:\n%s", pszName, pszFile, nLine, LocksHeld());
     abort();
 }
 
@@ -181,7 +181,7 @@ void AssertLockNotHeldInternal(const char* pszName, const char* pszFile, int nLi
 {
     for (const std::pair<void*, CLockLocation>& i : g_lockstack) {
         if (i.first == cs) {
-            tfm::format(std::cerr, "Assertion failed: lock %s held in %s:%i; locks held:\n%s", pszName, pszFile, nLine, LocksHeld().c_str());
+            tfm::format(std::cerr, "Assertion failed: lock %s held in %s:%i; locks held:\n%s", pszName, pszFile, nLine, LocksHeld());
             abort();
         }
     }