configure_make: use CMAKE_C_COMPILER_TARGET to detect cross-compilation

Currently, the only way to cross-compile using vcpkg_configure_make is
to use a gcc cross toolchain with the target as the prefix.

This is not how you cross compile with clang--with clang you set
CMAKE_<LANG>_COMPILER_TARGET. This detects this from the toolchain file
and passes it along

scripts/cmake/vcpkg_configure_make.cmake

@@ -399,7 +399,9 @@ function(vcpkg_configure_make)
             # This is used via --host as a prefix for all other bin tools as well. 
             # Setting the compiler directly via CC=arm-linux-gnueabihf-gcc does not work acording to: 
             # https://www.gnu.org/software/autoconf/manual/autoconf-2.65/html_node/Specifying-Target-Triplets.html
-            if(VCPKG_DETECTED_CMAKE_C_COMPILER MATCHES "([^\/]*)-gcc$" AND CMAKE_MATCH_1)
+            if (VCPKG_DETECTED_CMAKE_C_COMPILER_TARGET)
+                set(arg_BUILD_TRIPLET "--host=${VCPKG_DETECTED_CMAKE_C_COMPILER_TARGET}") # (Host activates crosscompilation; The name given here is just the prefix of the host tools for the target)
+            elseif(VCPKG_DETECTED_CMAKE_C_COMPILER MATCHES "([^\/]*)-gcc$" AND CMAKE_MATCH_1)
                 set(arg_BUILD_TRIPLET "--host=${CMAKE_MATCH_1}") # (Host activates crosscompilation; The name given here is just the prefix of the host tools for the target)
             endif()
             debug_message("Using make triplet: ${arg_BUILD_TRIPLET}")
@@ -441,7 +443,7 @@ function(vcpkg_configure_make)
         # Remove full filepaths due to spaces and prepend filepaths to PATH (cross-compiling tools are unlikely on path by default)
         set(progs VCPKG_DETECTED_CMAKE_C_COMPILER VCPKG_DETECTED_CMAKE_CXX_COMPILER VCPKG_DETECTED_CMAKE_AR
                   VCPKG_DETECTED_CMAKE_LINKER VCPKG_DETECTED_CMAKE_RANLIB VCPKG_DETECTED_CMAKE_OBJDUMP
-                  VCPKG_DETECTED_CMAKE_STRIP VCPKG_DETECTED_CMAKE_NM VCPKG_DETECTED_CMAKE_DLLTOOL VCPKG_DETECTED_CMAKE_RC_COMPILER)
+                  VCPKG_DETECTED_CMAKE_STRIP VCPKG_DETECTED_CMAKE_NM VCPKG_DETECTED_CMAKE_DLLTOOL VCPKG_DETECTED_CMAKE_RC_COMPILER VCPKG_DETECTED_CMAKE_C_COMPILER_TARGET)
         foreach(prog IN LISTS progs)
             set(filepath "${${prog}}")
             if(filepath MATCHES " ")