CLI: increase default value of Xms option

According to the preloader's "-measure" option, just the raw class files
occupy ~50 Mb during compilation of hello world (~55 Mb for K2). So 32M
is a very outdated value for Xms. This change sets it to something more
reasonable to hopefully avoid unnecessary GCs and thus help with
performance and potentially with OOMs (KT-58690).

 #KT-58690

compiler/cli/bin/kotlinc

@@ -39,7 +39,7 @@ if $cygwin; then
     KOTLIN_HOME=`cygpath --windows --short-name "$KOTLIN_HOME"`
 fi
 
-[ -n "$JAVA_OPTS" ] || JAVA_OPTS="-Xmx256M -Xms32M"
+[ -n "$JAVA_OPTS" ] || JAVA_OPTS="-Xmx256M -Xms128M"
 
 declare -a java_args
 declare -a kotlin_args

compiler/cli/bin/kotlinc.bat

@@ -20,7 +20,7 @@ if not "%JAVA_HOME%"=="" (
 )
 
 rem We use the value of the JAVA_OPTS environment variable if defined
-if "%JAVA_OPTS%"=="" set JAVA_OPTS=-Xmx256M -Xms32M
+if "%JAVA_OPTS%"=="" set JAVA_OPTS=-Xmx256M -Xms128M
 
 rem Iterate through arguments and split them into java and kotlin ones
 :loop