gcc-analyzer warnings for Arx in branch 1.2.1

• -Wanalyzer-allocation-size [docs] (1)
• -Wanalyzer-fd-leak [docs] (1)
• -Wanalyzer-fd-use-without-check [docs] (1)
• -Wanalyzer-use-after-free [docs] (1)
• -Wstringop-overflow= [docs] (1)
• -Wanalyzer-malloc-leak [docs] (17)
• -Wanalyzer-null-dereference [docs] (33)
• -Wanalyzer-possible-null-dereference [docs] (77)
• -Wanalyzer-use-of-uninitialized-value [docs] (130)
• -Wanalyzer-possible-null-argument [docs] (187)