vxOpenLibm - v1.0.1-rc0 : enable LTO support

*fix*
> [patches]
  | [cmake] force use SH4A-NOFPU target
  | [cmake] force LTO as default
  | [cmake] use `sh-elf-vhex-gcc-ar` instead of `sh-elf-vhex-ar` to magically support LTO plugins

Author: YannMagnin

patches/CMakeLists.txt

@@ -202,16 +202,24 @@ add_compile_options(
     -Wno-implicit-function-declaration
     -Wall
     -Wextra
+    -Os
     -fPIC
     -ffreestanding
+    -flto
     -nostdlib
-    -m3
     -mb
+    -m4-nofpu
     -std=c99
     -fno-gnu89-inline
     -fno-builtin
-    -O3
 )
+
+# Generate the archive with gcc-ar instead of ar as it will load the LTO
+# plugin which is required to generate a usable archive.
+set(CMAKE_C_ARCHIVE_CREATE "${CMAKE_C_COMPILER_AR} qcs <TARGET> <OBJECTS>")
+# Also the ranlib rule (useless because ar is passed the s flag anyway)
+set(CMAKE_C_ARCHIVE_FINISH "${CMAKE_C_COMPILER_RANLIB} <TARGET>")
+
 add_library(openlibm ${VXOPENLIBM_SOURCES})
 
 ## install configuration