common : use cpp-httplib as a cURL alternative for downloads (ggml-org#16185)

* vendor : update httplib

Signed-off-by: Adrien Gallouët <[email protected]>

* common : use cpp-httplib as a cURL alternative for downloads

The existing cURL implementation is intentionally left untouched to
prevent any regressions and to allow for safe, side-by-side testing by
toggling the `LLAMA_CURL` CMake option.

Signed-off-by: Adrien Gallouët <[email protected]>

* ggml : Bump to Windows 10

Signed-off-by: Adrien Gallouët <[email protected]>

---------

Signed-off-by: Adrien Gallouët <[email protected]>

Author: angt

common/CMakeLists.txt

@@ -87,7 +87,39 @@ if (LLAMA_CURL)
     target_compile_definitions(${TARGET} PUBLIC LLAMA_USE_CURL)
     include_directories(${CURL_INCLUDE_DIRS})
     set(LLAMA_COMMON_EXTRA_LIBS ${LLAMA_COMMON_EXTRA_LIBS} ${CURL_LIBRARIES})
-endif ()
+else()
+    find_package(OpenSSL)
+    if (OpenSSL_FOUND)
+        include(CheckCSourceCompiles)
+        set(CMAKE_REQUIRED_INCLUDES ${OPENSSL_INCLUDE_DIR})
+        check_c_source_compiles("
+        #include <openssl/opensslv.h>
+        #if defined(OPENSSL_IS_BORINGSSL) || defined(LIBRESSL_VERSION_NUMBER)
+        #    if OPENSSL_VERSION_NUMBER < 0x1010107f
+        #        error bad version
+        #    endif
+        #else
+        #    if OPENSSL_VERSION_NUMBER < 0x30000000L
+        #        error bad version
+        #    endif
+        #endif
+        int main() { return 0; }
+        " OPENSSL_VERSION_SUPPORTED)
+        if (OPENSSL_VERSION_SUPPORTED)
+            message(STATUS "OpenSSL found: ${OPENSSL_VERSION}")
+            target_compile_definitions(${TARGET} PUBLIC CPPHTTPLIB_OPENSSL_SUPPORT)
+            target_link_libraries(${TARGET} PUBLIC OpenSSL::SSL OpenSSL::Crypto)
+            if (APPLE AND CMAKE_SYSTEM_NAME STREQUAL "Darwin")
+                target_compile_definitions(${TARGET} PUBLIC CPPHTTPLIB_USE_CERTS_FROM_MACOSX_KEYCHAIN)
+                find_library(CORE_FOUNDATION_FRAMEWORK CoreFoundation REQUIRED)
+                find_library(SECURITY_FRAMEWORK Security REQUIRED)
+                target_link_libraries(${TARGET} PUBLIC ${CORE_FOUNDATION_FRAMEWORK} ${SECURITY_FRAMEWORK})
+            endif()
+        endif()
+    else()
+        message(STATUS "OpenSSL not found, SSL support disabled")
+    endif()
+endif()
 
 if (LLAMA_LLGUIDANCE)
     include(ExternalProject)