bshell.runtime: add a compiler option for disabling floating-point usage

bshell.runtime/CMakeLists.txt

@@ -24,5 +24,6 @@ endif ()
 target_include_directories(bshell.runtime PUBLIC ${CMAKE_CURRENT_SOURCE_DIR}/include)
 target_compile_definitions(bshell.runtime PUBLIC
 	BSHELL_VERSION="${bshell_version}"
+	BSHELL_ENABLE_FLOATING_POINT=${bshell_enable_floating_point}
 	BSHELL_INTERACTIVE=${bshell_interactive}
 	BSHELL_VERBOSE=${bshell_verbose})

bshell.runtime/parse/lex/lex.c

@@ -653,6 +653,7 @@ bool string_is_valid_number(
 	}
 
 	char *ep = NULL;
+#if BSHELL_ENABLE_FLOATING_POINT == 1
 	double dvalue = strtod(s, &ep);
 	if (string_could_be_double(s) && *ep == '\0') {
 		if (out) {
@@ -665,6 +666,7 @@ bool string_is_valid_number(
 
 		return true;
 	}
+#endif
 
 	int base = get_int_base_by_prefix(&s);