compiler: never omit assertions if using a static analysis tool

Assertions help both Coverity and the clang static analyzer avoid
false positives, but on the other hand both are confused when
the condition is compiled as (void)(x != FOO).  Always expand
assertion macros when using Coverity or clang, through a new
QEMU_STATIC_ANALYSIS preprocessor symbol.

This fixes a couple false positives in TCG.
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

include/qemu/compiler.h

@@ -3,6 +3,9 @@
 #ifndef COMPILER_H
 #define COMPILER_H
 
+#if defined __clang_analyzer__ || defined __COVERITY__
+#define QEMU_STATIC_ANALYSIS 1
+#endif
 
 /*----------------------------------------------------------------------------
 | The macro QEMU_GNUC_PREREQ tests for minimum version of the GNU C compiler.

tcg/tcg.h

@@ -191,7 +191,7 @@ typedef uint64_t tcg_insn_unit;
 #endif
 
 
-#ifdef CONFIG_DEBUG_TCG
+#if defined CONFIG_DEBUG_TCG || defined QEMU_STATIC_ANALYSIS
 # define tcg_debug_assert(X) do { assert(X); } while (0)
 #elif QEMU_GNUC_PREREQ(4, 5)
 # define tcg_debug_assert(X) \