internal/rosa/cmake: implicit CMAKE_BUILD_TYPE

Lack of this behaviour is a holdover from when the helper was first split from the (now removed) LLVM helper.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/rosa/zlib.go

@@ -13,8 +13,6 @@ func (t Toolchain) newZlib() (pkg.Artifact, string) {
 		pkg.TarGzip,
 	), nil, &CMakeHelper{
 		Cache: []KV{
-			{"CMAKE_BUILD_TYPE", "Release"},
-
 			{"CMAKE_C_FLAGS", "-fPIC"},
 			{"ZLIB_BUILD_TESTING", "ON"},
 			{"ZLIB_BUILD_SHARED", "ON"},