Parse the timezone myself, instead of using the broken strptime

See

https://lab.louiz.org/louiz/biboumi/issues/3215
https://github.com/andikleen/glibc/blob/master/time/strptime_l.c#L746-L747

for why strptime() sucks

We use std::get_time now, to parse the date and time. And we parse the
timezone by hand.

fix #3215

louloulibs/utils/time.cpp

@@ -1,6 +1,10 @@
 #include <utils/time.hpp>
 #include <time.h>
 
+#include <sstream>
+#include <iomanip>
+#include <locale>
+
 namespace utils
 {
 std::string to_string(const std::time_t& timestamp)
@@ -14,12 +18,42 @@ std::string to_string(const std::time_t& timestamp)
 
 std::time_t parse_datetime(const std::string& stamp)
 {
-  auto stamp2 = stamp.substr(0, stamp.size() - 1) + "z";
-  struct tm tm;
-  if (!::strptime(stamp2.data(), "%FT%T%Z", &tm))
+  static const char* format = "%Y-%m-%dT%H:%M:%S";
+  std::tm t = {};
+  std::istringstream ss(stamp);
+  ss.imbue(std::locale("en_US.utf-8"));
+
+  std::string timezone;
+  ss >> std::get_time(&t, format) >> timezone;
+  if (ss.fail())
     return -1;
-  auto res = ::timegm(&tm);
-  return res;
+
+  if (timezone.empty())
+    return -1;
+
+  if (timezone.compare(0, 1, "Z") != 0)
+    {
+      std::stringstream tz_ss;
+      tz_ss << timezone;
+      int multiplier = -1;
+      char prefix;
+      int hours;
+      char sep;
+      int minutes;
+      tz_ss >> prefix >> hours >> sep >> minutes;
+      if (tz_ss.fail())
+        return -1;
+      if (prefix == '-')
+        multiplier = +1;
+      else if (prefix != '+')
+        return -1;
+
+      t.tm_hour += multiplier * hours;
+      t.tm_min += multiplier * minutes;
+    }
+  return ::timegm(&t);
 }
 
 }
+
+