Add default feature for JIT

When building servo on Linux with the profile `production-stripped`,
disabling JIT with this change shaves off 9MiB from the servo binary
size, which is around 10%.

Signed-off-by: Jonathan Schwender <schwenderjonathan@gmail.com>

Author: jschwe

mozjs-sys/Cargo.toml

@@ -2,7 +2,7 @@
 name = "mozjs_sys"
 description = "System crate for the Mozilla SpiderMonkey JavaScript engine."
 repository.workspace = true
-version = "0.128.13-0"
+version = "0.128.13-1"
 authors = ["Mozilla"]
 links = "mozjs"
 license.workspace = true
@@ -22,8 +22,10 @@ name = "mozjs_sys"
 doctest = false
 
 [features]
+default = ["jit"]
 debugmozjs = []
 profilemozjs = []
+jit = []
 jitspew = []
 crown = []
 oom_with_hook = []

mozjs-sys/build.rs

@@ -405,6 +405,9 @@ fn should_build_from_source() -> bool {
     } else if env::var_os("CARGO_FEATURE_DEBUGMOZJS").is_some() {
         println!("debug-mozjs feature is enabled. Building from source directly.");
         true
+    } else if !env::var_os("CARGO_FEATURE_JIT").is_some() {
+        println!("jit feature is NOT enabled. Building from source directly.");
+        true
     } else {
         false
     }

mozjs-sys/makefile.cargo

@@ -11,6 +11,10 @@ CONFIGURE_FLAGS := \
 	--disable-shared-js \
 	--build-backends=RecursiveMake
 
+ifeq (,$(CARGO_FEATURE_JIT))
+    CONFIGURE_FLAGS += --disable-jit
+endif
+
 ifneq (,$(CARGO_FEATURE_JITSPEW))
     CONFIGURE_FLAGS += --enable-jitspew
 endif
@@ -63,7 +67,7 @@ ifneq ($(HOST),$(TARGET))
 	endif
 
 	ifeq (aarch64-unknown-linux-gnu,$(TARGET))
-	    # Reset TARGET variable because aarch64 target name used by Rust is not 
+	    # Reset TARGET variable because aarch64 target name used by Rust is not
 		# the same as the target name needed for the CXX toolchain.
 		TARGET = aarch64-linux-gnu
 	endif