[Bug] Heap fragmentation over time

[BlueAndi]

Its enough heap (sum of all available blocks) space available, but the largest block is lower than the requested size.
Note, the available heap in the log is lower than shown, because the ESP.availableHeap() returns more than malloc and new can allocate.

21342298   DEBUG   AsyncHttpClient.cpp:878      Available heap: 109500
21342414   ERROR   MemMon.cpp:67                Failed to allocate memory, size: 16717 bytes, caps: 0x0804, func: heap_caps_...
21342415   ERROR   MemMon.cpp:68                Largest available HEAP block: 16372 bytes
[21327591][E][AsyncTCP_TLS_Context.cpp:28] _handle_error(): [_startSSLClient():226]: (-32512) SSL - Memory allocation failed
[21327610][E][AsyncTCP.cpp:696] _sockIsWriteable(): TLS setup failed with error -32512, closing socket...
21342475   INFO    AsyncHttpClient.cpp:708      Disconnected from warnung.bund.de:443/api31/dashboard/097720000000.json.
21342476   DEBUG   AsyncHttpClient.cpp:709      Available heap: 109064
21342486   WARNING AsyncHttpClient.cpp:740      Error occurred: -11 - Not connected.
21342569   WARNING GrabViaRestPlugin.cpp:352    Connection error.
21342668   INFO    GrabViaRestPlugin.cpp:339    Connection closed.
21349474   INFO    AsyncHttpClient.cpp:336      Host: api.github.com
21349475   INFO    AsyncHttpClient.cpp:337      Port: 443
21349475   INFO    AsyncHttpClient.cpp:338      URI: /repos/BlueAndi/Pixelix
21349485   INFO    AsyncHttpClient.cpp:342      Authorization: -
21349506   INFO    AsyncHttpClient.cpp:877      Connecting to api.github.com:443/repos/BlueAndi/Pixelix.
21349506   DEBUG   AsyncHttpClient.cpp:878      Available heap: 109532
21349592   ERROR   MemMon.cpp:67                Failed to allocate memory, size: 16717 bytes, caps: 0x0804, func: heap_caps_...
21349592   ERROR   MemMon.cpp:68                Largest available HEAP block: 16372 bytes
[21334769][E][AsyncTCP_TLS_Context.cpp:28] _handle_error(): [_startSSLClient():226]: (-32512) SSL - Memory allocation failed
[21334787][E][AsyncTCP.cpp:696] _sockIsWriteable(): TLS setup failed with error -32512, closing socket...
21349653   INFO    AsyncHttpClient.cpp:708      Disconnected from api.github.com:443/repos/BlueAndi/Pixelix.
21349653   DEBUG   AsyncHttpClient.cpp:709      Available heap: 109384
21349664   WARNING AsyncHttpClient.cpp:740      Error occurred: -11 - Not connected.
21349676   WARNING GrabViaRestPlugin.cpp:352    Connection error.
21349776   INFO    GrabViaRestPlugin.cpp:339    Connection closed.