gcc-dev_unity_xtra warnings for Arx in branch 1.2.1

• -Wconditionally-supported [docs] (1)
• -Wstrict-aliasing [docs] (6)
• -Wunused-const-variable= [docs] (11)
• -Wuseless-cast [docs] (70)
• -Wold-style-cast [docs] (102)
• -Wpadded [docs] (291)
• -Wconversion [docs] (502)