fix(win): replace std::hex/std::dec with ipc::spec for MinGW compatibility (issue #171)

Replace I/O manipulators (std::hex, std::dec) with ipc::spec in log
statements. The ipc::fmt system does not support std::iostream
manipulators, which caused compilation failures under MinGW.

Changed files:
- src/libipc/platform/win/mutex.h (lines 78, 96)
- src/libipc/platform/win/semaphore.h (line 71)

The format spec "#x" produces output like "0x102" which matches
the original behavior:
- # flag adds the "0x" prefix automatically
- x outputs lowercase hexadecimal

Fixes: #171

src/libipc/platform/win/mutex.h

@@ -75,7 +75,7 @@ public:
                 }
                 break; // loop again
             default:
-                log.error("fail WaitForSingleObject[", ::GetLastError(), "]: 0x", std::hex, ret, std::dec);
+                log.error("fail WaitForSingleObject[", ::GetLastError(), "]: ", ipc::spec("#x")(ret));
                 return false;
             }
         }
@@ -93,7 +93,7 @@ public:
             unlock();
             LIBIPC_FALLTHROUGH;
         default:
-            log.error("fail WaitForSingleObject[", ::GetLastError(), "]: 0x", std::hex, ret, std::dec);
+            log.error("fail WaitForSingleObject[", ::GetLastError(), "]: ", ipc::spec("#x")(ret));
             throw std::system_error{static_cast<int>(ret), std::system_category()};
         }
     }

src/libipc/platform/win/semaphore.h

@@ -68,7 +68,7 @@ public:
             return false;
         case WAIT_ABANDONED:
         default:
-            log.error("fail WaitForSingleObject[", ::GetLastError(), "]: 0x", std::hex, ret, std::dec);
+            log.error("fail WaitForSingleObject[", ::GetLastError(), "]: ", ipc::spec("#x")(ret));
             return false;
         }
     }