fix(hsolver): replace std::vector<bool> with std::vector<int> in Davidson convergence flags

std::vector<bool> packs bits and is not thread-safe under concurrent
parallel writes from OpenMP, causing non-deterministic hangs/crashes
(e.g. 01_PW/035_PW_15_SO with many threads). Use std::vector<int>
for independent per-element writes in diago_david and diago_dav_subspace.

Author: Agent

source/source_hsolver/diago_dav_subspace.cpp

@@ -121,7 +121,7 @@ int Diago_DavSubspace<T, Device>::diag_once(const HPsiFunc& hpsi_func,
     std::vector<Real> eigenvalue_iter(this->nbase_x, 0.0);
 
     // convflag[m] = true if the m th band is convergent
-    std::vector<bool> convflag(this->n_band, false);
+    std::vector<int> convflag(this->n_band, 0);
 
     // unconv[m] store the number of the m th unconvergent band
     std::vector<int> unconv(this->n_band);

source/source_hsolver/diago_david.cpp

@@ -139,7 +139,7 @@ int DiagoDavid<T, Device>::diag_once(const HPsiFunc& hpsi_func,
     DiagoTrace trace("Davidson");
 
     // convflag[m] = true if the m th band is converged
-    std::vector<bool> convflag(nband, false);
+    std::vector<int> convflag(nband, 0);
     // unconv[m] store the number of the m th unconverged band
     std::vector<int> unconv(nband);