Cleanups of SIMDE_BUG_* definitions (#680)

* operationalize clang bug 44589
* remove unused bug references

simde-common.h

@@ -777,23 +777,14 @@ HEDLEY_DIAGNOSTIC_POP
 #      define SIMDE_BUG_GCC_REV_247851
 #    endif
 #    if !HEDLEY_GCC_VERSION_CHECK(10,0,0)
-#      define SIMDE_BUG_GCC_REV_274313
 #      define SIMDE_BUG_GCC_91341
 #    endif
-#    if !HEDLEY_GCC_VERSION_CHECK(9,0,0) && defined(SIMDE_ARCH_AARCH64)
-#      define SIMDE_BUG_GCC_ARM_SHIFT_SCALAR
-#    endif
 #    if defined(SIMDE_ARCH_X86) && !defined(SIMDE_ARCH_AMD64)
 #      define SIMDE_BUG_GCC_94482
 #    endif
 #    if (defined(SIMDE_ARCH_X86) && !defined(SIMDE_ARCH_AMD64)) || defined(SIMDE_ARCH_SYSTEMZ)
 #      define SIMDE_BUG_GCC_53784
 #    endif
-#    if defined(SIMDE_ARCH_X86) || defined(SIMDE_ARCH_AMD64)
-#      if HEDLEY_GCC_VERSION_CHECK(4,3,0) /* -Wsign-conversion */
-#        define SIMDE_BUG_GCC_95144
-#      endif
-#    endif
 #    if !HEDLEY_GCC_VERSION_CHECK(9,4,0) && defined(SIMDE_ARCH_AARCH64)
 #      define SIMDE_BUG_GCC_94488
 #    endif
@@ -825,22 +816,13 @@ HEDLEY_DIAGNOSTIC_POP
 #      define SIMDE_BUG_CLANG_POWER9_16x4_BAD_SHIFT
 #    endif
 #    if defined(SIMDE_ARCH_X86) || defined(SIMDE_ARCH_AMD64)
-#      if HEDLEY_HAS_WARNING("-Wsign-conversion") && SIMDE_DETECT_CLANG_VERSION_NOT(11,0,0)
-#        define SIMDE_BUG_CLANG_45931
+#      if HEDLEY_HAS_WARNING("-Wvector-conversion") && SIMDE_DETECT_CLANG_VERSION_NOT(11,0,0)
+#        define SIMDE_BUG_CLANG_44589
 #      endif
 #    endif
-#    define SIMDE_BUG_CLANG_45959
-#  elif defined(HEDLEY_MSVC_VERSION)
-#    if defined(SIMDE_ARCH_X86)
-#      define SIMDE_BUG_MSVC_ROUND_EXTRACT
-#    endif
 #  elif defined(HEDLEY_INTEL_VERSION)
 #    define SIMDE_BUG_INTEL_857088
 #  endif
-#  if defined(HEDLEY_EMSCRIPTEN_VERSION)
-#    define SIMDE_BUG_EMSCRIPTEN_MISSING_IMPL /* Placeholder for (as yet) unfiled issues. */
-#    define SIMDE_BUG_EMSCRIPTEN_5242
-#  endif
 #endif
 
 /* GCC and Clang both have the same issue:

x86/sse.h

@@ -2331,8 +2331,7 @@ simde_mm_extract_pi16 (simde__m64 a, const int imm8)
   return a_.i16[imm8];
 }
 #if defined(SIMDE_X86_SSE_NATIVE) && defined(SIMDE_X86_MMX_NATIVE) && !defined(HEDLEY_PGI_VERSION)
-#  if HEDLEY_HAS_WARNING("-Wvector-conversion")
-     /* https://bugs.llvm.org/show_bug.cgi?id=44589 */
+#  if defined(SIMDE_BUG_CLANG_44589)
 #    define simde_mm_extract_pi16(a, imm8) ( \
          HEDLEY_DIAGNOSTIC_PUSH \
          _Pragma("clang diagnostic ignored \"-Wvector-conversion\"") \
@@ -2365,8 +2364,7 @@ simde_mm_insert_pi16 (simde__m64 a, int16_t i, const int imm8)
   return simde__m64_from_private(r_);
 }
 #if defined(SIMDE_X86_SSE_NATIVE) && defined(SIMDE_X86_MMX_NATIVE) && !defined(__PGI)
-#  if HEDLEY_HAS_WARNING("-Wvector-conversion")
-     /* https://bugs.llvm.org/show_bug.cgi?id=44589 */
+#  if defined(SIMDE_BUG_CLANG_44589)
 #    define ssimde_mm_insert_pi16(a, i, imm8) ( \
          HEDLEY_DIAGNOSTIC_PUSH \
          _Pragma("clang diagnostic ignored \"-Wvector-conversion\"") \