Add pseudo flag `-fast-build`

src/main.cpp

@@ -399,6 +399,8 @@ enum BuildFlagKind {
 
 	BuildFlag_Sanitize,
 
+	BuildFlag_FastBuild,
+
 #if defined(GB_SYSTEM_WINDOWS)
 	BuildFlag_IgnoreVsSearch,
 	BuildFlag_ResourceFile,
@@ -605,6 +607,9 @@ gb_internal bool parse_build_flags(Array<String> args) {
 
 	add_flag(&build_flags, BuildFlag_Sanitize,                str_lit("sanitize"),                  BuildFlagParam_String,  Command__does_build, true);
 
+	add_flag(&build_flags, BuildFlag_FastBuild,               str_lit("fast-build"),                BuildFlagParam_String,  Command__does_build);
+
+
 #if defined(GB_SYSTEM_WINDOWS)
 	add_flag(&build_flags, BuildFlag_IgnoreVsSearch,          str_lit("ignore-vs-search"),          BuildFlagParam_None,    Command__does_build);
 	add_flag(&build_flags, BuildFlag_ResourceFile,            str_lit("resource"),                  BuildFlagParam_String,  Command__does_build);
@@ -1441,6 +1446,13 @@ gb_internal bool parse_build_flags(Array<String> args) {
 							}
 							break;
 
+
+						case BuildFlag_FastBuild:
+							build_context.custom_optimization_level = true;
+							build_context.optimization_level = -1;
+							build_context.use_separate_modules = true;
+							break;
+
 					#if defined(GB_SYSTEM_WINDOWS)
 						case BuildFlag_IgnoreVsSearch: {
 							GB_ASSERT(value.kind == ExactValue_Invalid);