cmake: fix ENABLE_DEBUG=ON builds in default/release mode

`ENABLE_DEBUG=ON` enables curl-level debug features. Building and
running the curl test suite requires setting this option.

Before this patch, while building the `testdeps` target with debug
features on with the default ('Release') CMake config, the build stopped
with this linker error:
```
ld: CMakeFiles/unit1395.dir/unit1395.c.o: in function `test':
unit1395.c:(.text+0x1a0): undefined reference to `dedotdotify'
A failure has been detected in another branch of the parallel make
```
Ref: https://github.com/curl/curl/actions/runs/9037287098/job/24835990826#step:3:2483

It happened because `dedotdotify` compiled as a static function into
`libcurlu` due to the undefined `DEBUGBUILD` macro. Then `unit1395`
failed to link it.

Even though the build requires the `DEBUGBUILD` macro, our CMake logic
defined it when building with CMake's 'Debug' configuration only. That
configuration is not required to build or run the test suite, nor to use
curl-level debug features.

This patch fixes this by always defining `DEBUGBUILD` when setting
`ENABLE_DEBUG=ON`. Decoupling this custom option from the selected CMake
Release/Debug configuration.

This change may also allow dropping Debug mode in AppVeyor CMake builds,
possibly making them build faster and run smoother.

Also delete the internal variable `ENABLE_CURLDEBUG` which was a copy of
`ENABLE_DEBUG`. Use the latter everywhere instead.

Ref: curl#13583
Closes #xxxxx

CMake/CurlSymbolHiding.cmake

@@ -26,7 +26,7 @@ include(CheckCSourceCompiles)
 option(CURL_HIDDEN_SYMBOLS "Set to ON to hide libcurl internal symbols (=hide all symbols that aren't officially external)." ON)
 mark_as_advanced(CURL_HIDDEN_SYMBOLS)
 
-if(WIN32 AND ENABLE_CURLDEBUG)
+if(WIN32 AND ENABLE_DEBUG)
   # We need to export internal debug functions (e.g. curl_dbg_*), so disable
   # symbol hiding for debug builds.
   set(CURL_HIDDEN_SYMBOLS OFF)

CMakeLists.txt

@@ -119,13 +119,8 @@ option(ENABLE_CURLDEBUG "Set to ON to build with TrackMemory feature enabled" OF
 include(PickyWarnings)
 
 if(ENABLE_DEBUG)
-  # DEBUGBUILD will be defined only for Debug builds
-  set_property(DIRECTORY APPEND PROPERTY COMPILE_DEFINITIONS $<$<CONFIG:Debug>:DEBUGBUILD>)
-  set(ENABLE_CURLDEBUG ON)
-endif()
-
-if(ENABLE_CURLDEBUG)
-  set_property(DIRECTORY APPEND PROPERTY COMPILE_DEFINITIONS CURLDEBUG)
+  add_definitions("-DDEBUGBUILD")
+  add_definitions("-DCURLDEBUG")
 endif()
 
 # For debug libs and exes, add "-d" postfix

lib/CMakeLists.txt

@@ -58,7 +58,7 @@ if(BUILD_TESTING)
   target_compile_definitions(curlu PUBLIC UNITTESTS CURL_STATICLIB)
 endif()
 
-if(ENABLE_CURLDEBUG)
+if(ENABLE_DEBUG)
   # We must compile these sources separately to avoid memdebug.h redefinitions
   # applying to them.
   set_source_files_properties(memdebug.c curl_multibyte.c PROPERTIES SKIP_UNITY_BUILD_INCLUSION ON)

src/CMakeLists.txt

@@ -64,7 +64,7 @@ if(BUILD_STATIC_CURL)
   set(CURLX_CFILES ${CURLTOOL_LIBCURL_CFILES})
 endif()
 
-if(ENABLE_CURLDEBUG)
+if(ENABLE_DEBUG)
   # We must compile this source separately to avoid memdebug.h redefinitions
   # applying to them.
   set_source_files_properties(../lib/curl_multibyte.c PROPERTIES SKIP_UNITY_BUILD_INCLUSION ON)

tests/unit/CMakeLists.txt

@@ -33,7 +33,7 @@ include_directories(
   ${CURL_BINARY_DIR}/include      # To be able to reach "curl/curl.h"
 )
 
-if (ENABLE_CURLDEBUG) # running unittests require curl to compiled with CURLDEBUG
+if(ENABLE_DEBUG)  # running unittests require curl to compiled with CURLDEBUG
   foreach(_testfile ${UNITPROGS})
     add_executable(${_testfile} EXCLUDE_FROM_ALL ${_testfile}.c ${UNITFILES})
     add_dependencies(testdeps ${_testfile})