build: produce shared objects for spice.exe / spice_laa.exe, disable 64-bit winxp builds (#744)

to speed up clean builds. GitHub CI time went from 20 minutes -> 10
minutes.

src/spice2x/util/sysutils.cpp

@@ -589,6 +589,24 @@ namespace sysutils {
             (void**)&EnumDisplayDevicesA_orig);
     }
 
+    bool is_large_address_aware() {
+        auto image_base = reinterpret_cast<const uint8_t *>(GetModuleHandleW(nullptr));
+        if (image_base == nullptr) {
+            return false;
+        }
+        auto dos_header = reinterpret_cast<const IMAGE_DOS_HEADER *>(image_base);
+        if (dos_header->e_magic != IMAGE_DOS_SIGNATURE) {
+            return false;
+        }
+        auto nt_headers = reinterpret_cast<const IMAGE_NT_HEADERS *>(
+                image_base + dos_header->e_lfanew);
+        if (nt_headers->Signature != IMAGE_NT_SIGNATURE) {
+            return false;
+        }
+        return (nt_headers->FileHeader.Characteristics
+                & IMAGE_FILE_LARGE_ADDRESS_AWARE) != 0;
+    }
+
 #if !SPICE_XP
 
     bool is_running_as_admin() {

src/spice2x/util/sysutils.h

@@ -20,6 +20,10 @@ namespace sysutils {
 
     const std::vector<MonitorEntry> &enumerate_monitors();
 
+    // reads the running module's PE header to determine whether the
+    // IMAGE_FILE_LARGE_ADDRESS_AWARE bit is set (i.e. spice_laa.exe)
+    bool is_large_address_aware();
+
     extern std::string SECOND_MONITOR_OVERRIDE;
     void hook_EnumDisplayDevicesA();